diff --git a/gulpfile.js b/gulpfile.js
index 769c665..7e0f75d 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -28,12 +28,12 @@ function debugify(sourceName, fileName, needsContext) {
   if (!fileName)
     fileName = sourceName;
 
-  var options = {
-    entry: './entrypoints/' + sourceName + '-index.js',
+  const options = {
+    entry: `./entrypoints/${sourceName}-index.js`,
     format: 'iife',
     moduleName: 'webcomponentsjs',
     sourceMap: true
-  }
+  };
 
   // The es6-promise polyfill needs to set the correct context.
   // See https://github.com/rollup/rollup/wiki/Troubleshooting#this-is-undefined
@@ -42,11 +42,8 @@ function debugify(sourceName, fileName, needsContext) {
   }
 
   return rollup(options)
-  .pipe(source(sourceName +'-index.js'))
-  .pipe(buffer())
-  .pipe(sourcemaps.init({loadMaps: true}))
+  .pipe(source(`${sourceName}-index.js`), 'entrypoints')
   .pipe(rename(fileName + '.js'))
-  .pipe(sourcemaps.write('.'))
   .pipe(gulp.dest('./'))
 }
 
@@ -160,36 +157,32 @@ gulp.task('refresh-bower', () => {
   });
 });
 
-gulp.task('webcomponents-debug', () => {
-  return rollup({
-    entry: './entrypoints/webcomponents-hi-sd-ce-pf-index.js',
-    format: 'iife',
-    moduleName: 'webcomponentsjs',
-    context: 'window'
-  })
-  .pipe(source('webcomponents-hi-sd-ce-pf-index.js', 'entrypoints'))
-  .pipe(rename('webcomponents-debug.js'))
-  .pipe(gulp.dest('.'))
-});
-
 gulp.task('default', (cb) => {
-  runseq('refresh-bower', ['webcomponents-debug', 'closure'], cb);
+  runseq('refresh-bower', 'closure', cb);
 });
 
-gulp.task('debug', [
+gulp.task('clean-builds', () => {
+  return del(['webcomponents*.js{,.map}', '!webcomponents-loader.js']);
+})
+
+gulp.task('debug', (cb) => {
+  const tasks = [
     'debugify-hi',
     'debugify-hi-ce',
     'debugify-hi-sd-ce',
     'debugify-hi-sd-ce-pf',
     'debugify-sd-ce'
-  ]);
+  ];
+  runseq('clean-builds', tasks, cb);
+});
 
 gulp.task('closure', (cb) => {
-  runseq(...[
-      'closurify-hi',
-      'closurify-hi-ce',
-      'closurify-hi-sd-ce',
-      'closurify-hi-sd-ce-pf',
-      'closurify-sd-ce'
-    ], cb);
+  const tasks = [
+    'closurify-hi',
+    'closurify-hi-ce',
+    'closurify-hi-sd-ce',
+    'closurify-hi-sd-ce-pf',
+    'closurify-sd-ce'
+  ];
+  runseq('clean-builds', ...tasks, cb);
 });
\ No newline at end of file
diff --git a/webcomponents-debug.js b/webcomponents-debug.js
deleted file mode 100644
index 24a2fdf..0000000
--- a/webcomponents-debug.js
+++ /dev/null
@@ -1,8532 +0,0 @@
-(function () {
-'use strict';
-
-/**
- * @license
- * Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
- * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
- * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
- * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
- * Code distributed by Google as part of the polymer project is also
- * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
- */
-
-(function(scope) {
-
-  'use strict';
-
-  // defaultPrevented is broken in IE.
-  // https://connect.microsoft.com/IE/feedback/details/790389/event-defaultprevented-returns-false-after-preventdefault-was-called
-  var workingDefaultPrevented = (function() {
-    var e = document.createEvent('Event');
-    e.initEvent('foo', true, true);
-    e.preventDefault();
-    return e.defaultPrevented;
-  })();
-
-  if (!workingDefaultPrevented) {
-    var origPreventDefault = Event.prototype.preventDefault;
-    Event.prototype.preventDefault = function() {
-      if (!this.cancelable) {
-        return;
-      }
-
-      origPreventDefault.call(this);
-
-      Object.defineProperty(this, 'defaultPrevented', {
-        get: function() {
-          return true;
-        },
-        configurable: true
-      });
-    };
-  }
-
-  var isIE = /Trident/.test(navigator.userAgent);
-
-  // CustomEvent constructor shim
-  if (!window.CustomEvent || isIE && (typeof window.CustomEvent !== 'function')) {
-    window.CustomEvent = function(inType, params) {
-      params = params || {};
-      var e = document.createEvent('CustomEvent');
-      e.initCustomEvent(inType, Boolean(params.bubbles), Boolean(params.cancelable), params.detail);
-      return e;
-    };
-    window.CustomEvent.prototype = window.Event.prototype;
-  }
-
-  // Event constructor shim
-  if (!window.Event || isIE && (typeof window.Event !== 'function')) {
-    var origEvent = window.Event;
-    window.Event = function(inType, params) {
-      params = params || {};
-      var e = document.createEvent('Event');
-      e.initEvent(inType, Boolean(params.bubbles), Boolean(params.cancelable));
-      return e;
-    };
-    if (origEvent) {
-      for (var i in origEvent) {
-        window.Event[i] = origEvent[i];
-      }
-    }
-    window.Event.prototype = origEvent.prototype;
-  }
-
-  if (!window.MouseEvent || isIE && (typeof window.MouseEvent !== 'function')) {
-    var origMouseEvent = window.MouseEvent;
-    window.MouseEvent = function(inType, params) {
-      params = params || {};
-      var e = document.createEvent('MouseEvent');
-      e.initMouseEvent(inType,
-        Boolean(params.bubbles), Boolean(params.cancelable),
-        params.view || window, params.detail,
-        params.screenX, params.screenY, params.clientX, params.clientY,
-        params.ctrlKey, params.altKey, params.shiftKey, params.metaKey,
-        params.button, params.relatedTarget);
-      return e;
-    };
-    if (origMouseEvent) {
-      for (var i in origMouseEvent) {
-        window.MouseEvent[i] = origMouseEvent[i];
-      }
-    }
-    window.MouseEvent.prototype = origMouseEvent.prototype;
-  }
-
-  // ES6 stuff
-  if (!Array.from) {
-    Array.from = function (object) {
-      return [].slice.call(object);
-    };
-  }
-
-  if (!Object.assign) {
-    var assign = function(target, source) {
-      var n$ = Object.getOwnPropertyNames(source);
-      for (var i=0, p; i < n$.length; i++) {
-        p = n$[i];
-        target[p] = source[p];
-      }
-    };
-
-    Object.assign = function(target, sources) {
-      var args = [].slice.call(arguments, 1);
-      for (var i=0, s; i < args.length; i++) {
-        s = args[i];
-        if (s) {
-          assign(target, s);
-        }
-      }
-      return target;
-    };
-  }
-
-})(window.WebComponents);
-
-/**
- * @license
- * Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
- * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
- * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
- * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
- * Code distributed by Google as part of the polymer project is also
- * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
- */
-
-// minimal template polyfill
-(function() {
-
-  var needsTemplate = (typeof HTMLTemplateElement === 'undefined');
-
-  // NOTE: Patch document.importNode to work around IE11 bug that
-  // casues children of a document fragment imported while
-  // there is a mutation observer to not have a parentNode (!?!)
-  // It's important that this is the first patch to `importNode` so that
-  // dom produced for later patches is correct.
-  if (/Trident/.test(navigator.userAgent)) {
-    (function() {
-      var Native_importNode = Document.prototype.importNode;
-      Document.prototype.importNode = function() {
-        var n = Native_importNode.apply(this, arguments);
-        // Copy all children to a new document fragment since
-        // this one may be broken
-        if (n.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
-          var f = this.createDocumentFragment();
-          f.appendChild(n);
-          return f;
-        } else {
-          return n;
-        }
-      };
-    })();
-  }
-
-  // NOTE: we rely on this cloneNode not causing element upgrade.
-  // This means this polyfill must load before the CE polyfill and
-  // this would need to be re-worked if a browser supports native CE
-  // but not <template>.
-  var Native_cloneNode = Node.prototype.cloneNode;
-  var Native_createElement = Document.prototype.createElement;
-  var Native_importNode = Document.prototype.importNode;
-
-  // returns true if nested templates cannot be cloned (they cannot be on
-  // some impl's like Safari 8 and Edge)
-  // OR if cloning a document fragment does not result in a document fragment
-  var needsCloning = (function() {
-    if (!needsTemplate) {
-      var t = document.createElement('template');
-      var t2 = document.createElement('template');
-      t2.content.appendChild(document.createElement('div'));
-      t.content.appendChild(t2);
-      var clone = t.cloneNode(true);
-      return (clone.content.childNodes.length === 0 || clone.content.firstChild.content.childNodes.length === 0
-        || !(document.createDocumentFragment().cloneNode() instanceof DocumentFragment));
-    }
-  })();
-
-  var TEMPLATE_TAG = 'template';
-  var PolyfilledHTMLTemplateElement = function() {};
-
-  if (needsTemplate) {
-
-    var contentDoc = document.implementation.createHTMLDocument('template');
-    var canDecorate = true;
-
-    var templateStyle = document.createElement('style');
-    templateStyle.textContent = TEMPLATE_TAG + '{display:none;}';
-
-    var head = document.head;
-    head.insertBefore(templateStyle, head.firstElementChild);
-
-    /**
-      Provides a minimal shim for the <template> element.
-    */
-    PolyfilledHTMLTemplateElement.prototype = Object.create(HTMLElement.prototype);
-
-
-    // if elements do not have `innerHTML` on instances, then
-    // templates can be patched by swizzling their prototypes.
-    var canProtoPatch =
-      !(document.createElement('div').hasOwnProperty('innerHTML'));
-
-    /**
-      The `decorate` method moves element children to the template's `content`.
-      NOTE: there is no support for dynamically adding elements to templates.
-    */
-    PolyfilledHTMLTemplateElement.decorate = function(template) {
-      // if the template is decorated, return fast
-      if (template.content) {
-        return;
-      }
-      template.content = contentDoc.createDocumentFragment();
-      var child;
-      while (child = template.firstChild) {
-        template.content.appendChild(child);
-      }
-      // NOTE: prefer prototype patching for performance and
-      // because on some browsers (IE11), re-defining `innerHTML`
-      // can result in intermittent errors.
-      if (canProtoPatch) {
-        template.__proto__ = PolyfilledHTMLTemplateElement.prototype;
-      } else {
-        template.cloneNode = function(deep) {
-          return PolyfilledHTMLTemplateElement._cloneNode(this, deep);
-        };
-        // add innerHTML to template, if possible
-        // Note: this throws on Safari 7
-        if (canDecorate) {
-          try {
-            defineInnerHTML(template);
-          } catch (err) {
-            canDecorate = false;
-          }
-        }
-      }
-      // bootstrap recursively
-      PolyfilledHTMLTemplateElement.bootstrap(template.content);
-    };
-
-    function defineInnerHTML(obj) {
-      Object.defineProperty(obj, 'innerHTML', {
-        get: function() {
-          var o = '';
-          for (var e = this.content.firstChild; e; e = e.nextSibling) {
-            o += e.outerHTML || escapeData(e.data);
-          }
-          return o;
-        },
-        set: function(text) {
-          contentDoc.body.innerHTML = text;
-          PolyfilledHTMLTemplateElement.bootstrap(contentDoc);
-          while (this.content.firstChild) {
-            this.content.removeChild(this.content.firstChild);
-          }
-          while (contentDoc.body.firstChild) {
-            this.content.appendChild(contentDoc.body.firstChild);
-          }
-        },
-        configurable: true
-      });
-    }
-
-    defineInnerHTML(PolyfilledHTMLTemplateElement.prototype);
-
-    /**
-      The `bootstrap` method is called automatically and "fixes" all
-      <template> elements in the document referenced by the `doc` argument.
-    */
-    PolyfilledHTMLTemplateElement.bootstrap = function(doc) {
-      var templates = doc.querySelectorAll(TEMPLATE_TAG);
-      for (var i=0, l=templates.length, t; (i<l) && (t=templates[i]); i++) {
-        PolyfilledHTMLTemplateElement.decorate(t);
-      }
-    };
-
-    // auto-bootstrapping for main document
-    document.addEventListener('DOMContentLoaded', function() {
-      PolyfilledHTMLTemplateElement.bootstrap(document);
-    });
-
-    // Patch document.createElement to ensure newly created templates have content
-    Document.prototype.createElement = function() {
-      'use strict';
-      var el = Native_createElement.apply(this, arguments);
-      if (el.localName === 'template') {
-        PolyfilledHTMLTemplateElement.decorate(el);
-      }
-      return el;
-    };
-
-    var escapeDataRegExp = /[&\u00A0<>]/g;
-
-    function escapeReplace(c) {
-      switch (c) {
-        case '&':
-          return '&amp;';
-        case '<':
-          return '&lt;';
-        case '>':
-          return '&gt;';
-        case '\u00A0':
-          return '&nbsp;';
-      }
-    }
-
-    function escapeData(s) {
-      return s.replace(escapeDataRegExp, escapeReplace);
-    }
-  }
-
-  // make cloning/importing work!
-  if (needsTemplate || needsCloning) {
-
-    PolyfilledHTMLTemplateElement._cloneNode = function(template, deep) {
-      var clone = Native_cloneNode.call(template, false);
-      // NOTE: decorate doesn't auto-fix children because they are already
-      // decorated so they need special clone fixup.
-      if (this.decorate) {
-        this.decorate(clone);
-      }
-      if (deep) {
-        // NOTE: use native clone node to make sure CE's wrapped
-        // cloneNode does not cause elements to upgrade.
-        clone.content.appendChild(
-            Native_cloneNode.call(template.content, true));
-        // now ensure nested templates are cloned correctly.
-        this.fixClonedDom(clone.content, template.content);
-      }
-      return clone;
-    };
-
-    PolyfilledHTMLTemplateElement.prototype.cloneNode = function(deep) {
-      return PolyfilledHTMLTemplateElement._cloneNode(this, deep);
-    };
-
-    // Given a source and cloned subtree, find <template>'s in the cloned
-    // subtree and replace them with cloned <template>'s from source.
-    // We must do this because only the source templates have proper .content.
-    PolyfilledHTMLTemplateElement.fixClonedDom = function(clone, source) {
-      // do nothing if cloned node is not an element
-      if (!source.querySelectorAll) return;
-      // these two lists should be coincident
-      var s$ = source.querySelectorAll(TEMPLATE_TAG);
-      var t$ = clone.querySelectorAll(TEMPLATE_TAG);
-      for (var i=0, l=t$.length, t, s; i<l; i++) {
-        s = s$[i];
-        t = t$[i];
-        if (this.decorate) {
-          this.decorate(s);
-        }
-        t.parentNode.replaceChild(s.cloneNode(true), t);
-      }
-    };
-
-    // override all cloning to fix the cloned subtree to contain properly
-    // cloned templates.
-    Node.prototype.cloneNode = function(deep) {
-      var dom;
-      // workaround for Edge bug cloning documentFragments
-      // https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/8619646/
-      if (this instanceof DocumentFragment) {
-        if (!deep) {
-          return this.ownerDocument.createDocumentFragment();
-        } else {
-          dom = this.ownerDocument.importNode(this, true);
-        }
-      } else {
-        dom = Native_cloneNode.call(this, deep);
-      }
-      // template.content is cloned iff `deep`.
-      if (deep) {
-        PolyfilledHTMLTemplateElement.fixClonedDom(dom, this);
-      }
-      return dom;
-    };
-
-    // NOTE: we are cloning instead of importing <template>'s.
-    // However, the ownerDocument of the cloned template will be correct!
-    // This is because the native import node creates the right document owned
-    // subtree and `fixClonedDom` inserts cloned templates into this subtree,
-    // thus updating the owner doc.
-    Document.prototype.importNode = function(element, deep) {
-      if (element.localName === TEMPLATE_TAG) {
-        return PolyfilledHTMLTemplateElement._cloneNode(element, deep);
-      } else {
-        var dom = Native_importNode.call(this, element, deep);
-        if (deep) {
-          PolyfilledHTMLTemplateElement.fixClonedDom(dom, element);
-        }
-        return dom;
-      }
-    };
-
-    if (needsCloning) {
-      window.HTMLTemplateElement.prototype.cloneNode = function(deep) {
-        return PolyfilledHTMLTemplateElement._cloneNode(this, deep);
-      };
-    }
-  }
-
-  if (needsTemplate) {
-    window.HTMLTemplateElement = PolyfilledHTMLTemplateElement;
-  }
-
-})();
-
-!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):t.ES6Promise=e();}(window,function(){"use strict";function t(t){return"function"==typeof t||"object"==typeof t&&null!==t}function e(t){return"function"==typeof t}function n(t){I=t;}function r(t){J=t;}function o(){return function(){return process.nextTick(a)}}function i(){return"undefined"!=typeof H?function(){H(a);}:c()}function s(){var t=0,e=new V(a),n=document.createTextNode("");return e.observe(n,{characterData:!0}),function(){n.data=t=++t%2;}}function u(){var t=new MessageChannel;return t.port1.onmessage=a,function(){return t.port2.postMessage(0)}}function c(){var t=setTimeout;return function(){return t(a,1)}}function a(){for(var t=0;t<G;t+=2){var e=$[t],n=$[t+1];e(n),$[t]=void 0,$[t+1]=void 0;}G=0;}function f(){try{var t=require,e=t("vertx");return H=e.runOnLoop||e.runOnContext,i()}catch(n){return c()}}function l(t,e){var n=arguments,r=this,o=new 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w(t,n,r){n.constructor===t.constructor&&r===l&&n.constructor.resolve===h?b(t,n):r===it?j(t,it.error):void 0===r?S(t,n):e(r)?m(t,n,r):S(t,n);}function g(e,n){e===n?j(e,v()):t(n)?w(e,n,_(n)):S(e,n);}function A(t){t._onerror&&t._onerror(t._result),P(t);}function S(t,e){t._state===nt&&(t._result=e,t._state=rt,0!==t._subscribers.length&&J(P,t));}function j(t,e){t._state===nt&&(t._state=ot,t._result=e,J(A,t));}function E(t,e,n,r){var o=t._subscribers,i=o.length;t._onerror=null,o[i]=e,o[i+rt]=n,o[i+ot]=r,0===i&&t._state&&J(P,t);}function P(t){var e=t._subscribers,n=t._state;if(0!==e.length){for(var r=void 0,o=void 0,i=t._result,s=0;s<e.length;s+=3)r=e[s],o=e[s+n],r?x(n,r,o,i):o(i);t._subscribers.length=0;}}function T(){this.error=null;}function M(t,e){try{return t(e)}catch(n){return st.error=n,st}}function x(t,n,r,o){var i=e(r),s=void 0,u=void 0,c=void 0,a=void 0;if(i){if(s=M(r,o),s===st?(a=!0,u=s.error,s=null):c=!0,n===s)return void j(n,d())}else 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-
-/**
- * @license
- * Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
- * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
- * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
- * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
- * Code distributed by Google as part of the polymer project is also
- * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
- */
-(scope => {
-
-  /********************* base setup *********************/
-  const useNative = Boolean('import' in document.createElement('link'));
-
-  // Polyfill `currentScript` for browsers without it.
-  let currentScript = null;
-  if ('currentScript' in document === false) {
-    Object.defineProperty(document, 'currentScript', {
-      get() {
-        return currentScript ||
-          // NOTE: only works when called in synchronously executing code.
-          // readyState should check if `loading` but IE10 is
-          // interactive when scripts run so we cheat. This is not needed by
-          // html-imports polyfill but helps generally polyfill `currentScript`.
-          (document.readyState !== 'complete' ?
-            document.scripts[document.scripts.length - 1] : null);
-      },
-      configurable: true
-    });
-  }
-
-  /********************* path fixup *********************/
-  const ABS_URL_TEST = /(^\/)|(^#)|(^[\w-\d]*:)/;
-  const CSS_URL_REGEXP = /(url\()([^)]*)(\))/g;
-  const CSS_IMPORT_REGEXP = /(@import[\s]+(?!url\())([^;]*)(;)/g;
-  const STYLESHEET_REGEXP = /(<link[^>]*)(rel=['|"]?stylesheet['|"]?[^>]*>)/g;
-
-  // path fixup: style elements in imports must be made relative to the main
-  // document. We fixup url's in url() and @import.
-  const Path = {
-
-    fixUrls(element, base) {
-      if (element.href) {
-        element.setAttribute('href',
-          Path.replaceAttrUrl(element.getAttribute('href'), base));
-      }
-      if (element.src) {
-        element.setAttribute('src',
-          Path.replaceAttrUrl(element.getAttribute('src'), base));
-      }
-      if (element.localName === 'style') {
-        const r = Path.replaceUrls(element.textContent, base, CSS_URL_REGEXP);
-        element.textContent = Path.replaceUrls(r, base, CSS_IMPORT_REGEXP);
-      }
-    },
-
-    replaceUrls(text, linkUrl, regexp) {
-      return text.replace(regexp, (m, pre, url, post) => {
-        let urlPath = url.replace(/["']/g, '');
-        if (linkUrl) {
-          urlPath = Path.resolveUrl(urlPath, linkUrl);
-        }
-        return pre + '\'' + urlPath + '\'' + post;
-      });
-    },
-
-    replaceAttrUrl(text, linkUrl) {
-      if (text && ABS_URL_TEST.test(text)) {
-        return text;
-      } else {
-        return Path.resolveUrl(text, linkUrl);
-      }
-    },
-
-    resolveUrl(url, base) {
-      // Lazy feature detection.
-      if (Path.__workingURL === undefined) {
-        Path.__workingURL = false;
-        try {
-          const u = new URL('b', 'http://a');
-          u.pathname = 'c%20d';
-          Path.__workingURL = (u.href === 'http://a/c%20d');
-        } catch (e) {}
-      }
-
-      if (Path.__workingURL) {
-        return (new URL(url, base)).href;
-      }
-
-      // Fallback to creating an anchor into a disconnected document.
-      let doc = Path.__tempDoc;
-      if (!doc) {
-        doc = document.implementation.createHTMLDocument('temp');
-        Path.__tempDoc = doc;
-        doc.__base = doc.createElement('base');
-        doc.head.appendChild(doc.__base);
-        doc.__anchor = doc.createElement('a');
-      }
-      doc.__base.href = base;
-      doc.__anchor.href = url;
-      return doc.__anchor.href || url;
-    }
-  };
-
-  /********************* Xhr processor *********************/
-  const Xhr = {
-
-    async: true,
-
-    /**
-     * @param {!string} url
-     * @param {!function(!string, string=)} success
-     * @param {!function(!string)} fail
-     */
-    load(url, success, fail) {
-      if (!url) {
-        fail('error: href must be specified');
-      } else if (url.match(/^data:/)) {
-        // Handle Data URI Scheme
-        const pieces = url.split(',');
-        const header = pieces[0];
-        let resource = pieces[1];
-        if (header.indexOf(';base64') > -1) {
-          resource = atob(resource);
-        } else {
-          resource = decodeURIComponent(resource);
-        }
-        success(resource);
-      } else {
-        const request = new XMLHttpRequest();
-        request.open('GET', url, Xhr.async);
-        request.onload = () => {
-          // Servers redirecting an import can add a Location header to help us
-          // polyfill correctly. Handle relative and full paths.
-          let redirectedUrl = request.getResponseHeader('Location');
-          if (redirectedUrl && redirectedUrl.indexOf('/') === 0) {
-            // In IE location.origin might not work
-            // https://connect.microsoft.com/IE/feedback/details/1763802/location-origin-is-undefined-in-ie-11-on-windows-10-but-works-on-windows-7
-            const origin = (location.origin || location.protocol + '//' + location.host);
-            redirectedUrl = origin + redirectedUrl;
-          }
-          const resource = /** @type {string} */ (request.response || request.responseText);
-          if (request.status === 304 || request.status === 0 ||
-            request.status >= 200 && request.status < 300) {
-            success(resource, redirectedUrl);
-          } else {
-            fail(resource);
-          }
-        };
-        request.send();
-      }
-    }
-  };
-
-  /********************* importer *********************/
-
-  const isIE = /Trident/.test(navigator.userAgent) ||
-    /Edge\/\d./i.test(navigator.userAgent);
-
-  const importSelector = 'link[rel=import]';
-
-  // Used to disable loading of resources.
-  const importDisableType = 'import-disable';
-
-  const disabledLinkSelector = `link[rel=stylesheet][href][type=${importDisableType}]`;
-
-  const importDependenciesSelector = `${importSelector}, ${disabledLinkSelector},
-    style:not([type]), link[rel=stylesheet][href]:not([type]),
-    script:not([type]), script[type="application/javascript"],
-    script[type="text/javascript"]`;
-
-  const importDependencyAttr = 'import-dependency';
-
-  const rootImportSelector = `${importSelector}:not(${importDependencyAttr})`;
-
-  const pendingScriptsSelector = `script[${importDependencyAttr}]`;
-
-  const pendingStylesSelector = `style[${importDependencyAttr}],
-    link[rel=stylesheet][${importDependencyAttr}]`;
-
-  /**
-   * Importer will:
-   * - load any linked import documents (with deduping)
-   * - whenever an import is loaded, prompt the parser to try to parse
-   * - observe imported documents for new elements (these are handled via the
-   *   dynamic importer)
-   */
-  class Importer {
-    constructor() {
-      this.documents = {};
-      // Used to keep track of pending loads, so that flattening and firing of
-      // events can be done when all resources are ready.
-      this.inflight = 0;
-      this.dynamicImportsMO = new MutationObserver(m => this.handleMutations(m));
-      // 1. Load imports contents
-      // 2. Assign them to first import links on the document
-      // 3. Wait for import styles & scripts to be done loading/running
-      // 4. Fire load/error events
-      whenDocumentReady(() => {
-        // Observe changes on <head>.
-        this.dynamicImportsMO.observe(document.head, {
-          childList: true,
-          subtree: true
-        });
-        this.loadImports(document);
-      });
-    }
-
-    /**
-     * @param {!(HTMLDocument|DocumentFragment|Element)} doc
-     */
-    loadImports(doc) {
-      const links = /** @type {!NodeList<!HTMLLinkElement>} */
-        (doc.querySelectorAll(importSelector));
-      for (let i = 0, l = links.length; i < l; i++) {
-        this.loadImport(links[i]);
-      }
-    }
-
-    /**
-     * @param {!HTMLLinkElement} link
-     */
-    loadImport(link) {
-      const url = link.href;
-      // This resource is already being handled by another import.
-      if (this.documents[url] !== undefined) {
-        // If import is already loaded, we can safely associate it to the link
-        // and fire the load/error event.
-        const imp = this.documents[url];
-        if (imp && imp['__loaded']) {
-          link.import = imp;
-          this.fireEventIfNeeded(link);
-        }
-        return;
-      }
-      this.inflight++;
-      // Mark it as pending to notify others this url is being loaded.
-      this.documents[url] = 'pending';
-      Xhr.load(url, (resource, redirectedUrl) => {
-        const doc = this.makeDocument(resource, redirectedUrl || url);
-        this.documents[url] = doc;
-        this.inflight--;
-        // Load subtree.
-        this.loadImports(doc);
-        this.processImportsIfLoadingDone();
-      }, () => {
-        // If load fails, handle error.
-        this.documents[url] = null;
-        this.inflight--;
-        this.processImportsIfLoadingDone();
-      });
-    }
-
-    /**
-     * Creates a new document containing resource and normalizes urls accordingly.
-     * @param {string=} resource
-     * @param {string=} url
-     * @return {!DocumentFragment}
-     */
-    makeDocument(resource, url) {
-      if (!resource) {
-        return document.createDocumentFragment();
-      }
-
-      if (isIE) {
-        // <link rel=stylesheet> should be appended to <head>. Not doing so
-        // in IE/Edge breaks the cascading order. We disable the loading by
-        // setting the type before setting innerHTML to avoid loading
-        // resources twice.
-        resource = resource.replace(STYLESHEET_REGEXP, (match, p1, p2) => {
-          if (match.indexOf('type=') === -1) {
-            return `${p1} type=${importDisableType} ${p2}`;
-          }
-          return match;
-        });
-      }
-
-      let content;
-      const template = /** @type {!HTMLTemplateElement} */
-        (document.createElement('template'));
-      template.innerHTML = resource;
-      if (template.content) {
-        // This creates issues in Safari10 when used with shadydom (see #12).
-        content = template.content;
-      } else {
-        // <template> not supported, create fragment and move content into it.
-        content = document.createDocumentFragment();
-        while (template.firstChild) {
-          content.appendChild(template.firstChild);
-        }
-      }
-
-      // Support <base> in imported docs. Resolve url and remove its href.
-      const baseEl = content.querySelector('base');
-      if (baseEl) {
-        url = Path.replaceAttrUrl(baseEl.getAttribute('href'), url);
-        baseEl.removeAttribute('href');
-      }
-
-      const n$ = /** @type {!NodeList<!(HTMLLinkElement|HTMLScriptElement|HTMLStyleElement)>} */
-        (content.querySelectorAll(importDependenciesSelector));
-      // For source map hints.
-      let inlineScriptIndex = 0;
-      for (let i = 0, l = n$.length, n; i < l && (n = n$[i]); i++) {
-        // Listen for load/error events, then fix urls.
-        whenElementLoaded(n);
-        Path.fixUrls(n, url);
-        // Mark for easier selectors.
-        n.setAttribute(importDependencyAttr, '');
-        // Generate source map hints for inline scripts.
-        if (n.localName === 'script' && !n.src && n.textContent) {
-          const num = inlineScriptIndex ? `-${inlineScriptIndex}` : '';
-          const content = n.textContent + `\n//# sourceURL=${url}${num}.js\n`;
-          // We use the src attribute so it triggers load/error events, and it's
-          // easier to capture errors (e.g. parsing) like this.
-          n.setAttribute('src', 'data:text/javascript;charset=utf-8,' + encodeURIComponent(content));
-          n.textContent = '';
-          inlineScriptIndex++;
-        }
-      }
-      return content;
-    }
-
-    /**
-     * Waits for loaded imports to finish loading scripts and styles, then fires
-     * the load/error events.
-     */
-    processImportsIfLoadingDone() {
-      // Wait until all resources are ready, then load import resources.
-      if (this.inflight) {
-        return;
-      }
-
-      // Stop observing, flatten & load resource, then restart observing <head>.
-      this.dynamicImportsMO.disconnect();
-      this.flatten(document);
-      // We wait for styles to load, and at the same time we execute the scripts,
-      // then fire the load/error events for imports to have faster whenReady
-      // callback execution.
-      // NOTE: This is different for native behavior where scripts would be
-      // executed after the styles before them are loaded.
-      // To achieve that, we could select pending styles and scripts in the
-      // document and execute them sequentially in their dom order.
-      let scriptsOk = false,
-        stylesOk = false;
-      const onLoadingDone = () => {
-        if (stylesOk && scriptsOk) {
-          // Restart observing.
-          this.dynamicImportsMO.observe(document.head, {
-            childList: true,
-            subtree: true
-          });
-          this.fireEvents();
-        }
-      };
-      this.waitForStyles(() => {
-        stylesOk = true;
-        onLoadingDone();
-      });
-      this.runScripts(() => {
-        scriptsOk = true;
-        onLoadingDone();
-      });
-    }
-
-    /**
-     * @param {!HTMLDocument} doc
-     */
-    flatten(doc) {
-      const n$ = /** @type {!NodeList<!HTMLLinkElement>} */
-        (doc.querySelectorAll(importSelector));
-      for (let i = 0, l = n$.length, n; i < l && (n = n$[i]); i++) {
-        const imp = this.documents[n.href];
-        n.import = /** @type {!Document} */ (imp);
-        if (imp && imp.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
-          // We set the .import to be the link itself, and update its readyState.
-          // Other links with the same href will point to this link.
-          this.documents[n.href] = n;
-          n.readyState = 'loading';
-          // Suppress Closure warning about incompatible subtype assignment.
-          ( /** @type {!HTMLElement} */ (n).import = n);
-          // Override baseURI so that link.import.baseURI can be used seemlessly
-          // on native or polyfilled html-imports.
-          Object.defineProperty(n, 'baseURI', {
-            get: () => n.href,
-            configurable: true,
-            enumerable: true
-          });
-          this.flatten(imp);
-          n.appendChild(imp);
-        }
-      }
-    }
-
-    /**
-     * Replaces all the imported scripts with a clone in order to execute them.
-     * Updates the `currentScript`.
-     * @param {!function()} callback
-     */
-    runScripts(callback) {
-      const s$ = document.querySelectorAll(pendingScriptsSelector);
-      const l = s$.length;
-      const cloneScript = i => {
-        if (i < l) {
-          // The pending scripts have been generated through innerHTML and
-          // browsers won't execute them for security reasons. We cannot use
-          // s.cloneNode(true) either, the only way to run the script is manually
-          // creating a new element and copying its attributes.
-          const s = s$[i];
-          const clone = /** @type {!HTMLScriptElement} */
-            (document.createElement('script'));
-          // Remove import-dependency attribute to avoid double cloning.
-          s.removeAttribute(importDependencyAttr);
-          for (let j = 0, ll = s.attributes.length; j < ll; j++) {
-            clone.setAttribute(s.attributes[j].name, s.attributes[j].value);
-          }
-          // Update currentScript and replace original with clone script.
-          currentScript = clone;
-          s.parentNode.replaceChild(clone, s);
-          whenElementLoaded(clone, () => {
-            currentScript = null;
-            cloneScript(i + 1);
-          });
-        } else {
-          callback();
-        }
-      };
-      cloneScript(0);
-    }
-
-    /**
-     * Waits for all the imported stylesheets/styles to be loaded.
-     * @param {!function()} callback
-     */
-    waitForStyles(callback) {
-      const s$ = /** @type {!NodeList<!(HTMLLinkElement|HTMLStyleElement)>} */
-        (document.querySelectorAll(pendingStylesSelector));
-      let pending = s$.length;
-      if (!pending) {
-        callback();
-        return;
-      }
-      // <link rel=stylesheet> should be appended to <head>. Not doing so
-      // in IE/Edge breaks the cascading order
-      // https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/10472273/
-      // If there is one <link rel=stylesheet> imported, we must move all imported
-      // links and styles to <head>.
-      const needsMove = isIE && !!document.querySelector(disabledLinkSelector);
-      for (let i = 0, l = s$.length, s; i < l && (s = s$[i]); i++) {
-        // Listen for load/error events, remove selector once is done loading.
-        whenElementLoaded(s, () => {
-          s.removeAttribute(importDependencyAttr);
-          if (--pending === 0) {
-            callback();
-          }
-        });
-        // Check if was already moved to head, to handle the case where the element
-        // has already been moved but it is still loading.
-        if (needsMove && s.parentNode !== document.head) {
-          // Replace the element we're about to move with a placeholder.
-          const placeholder = document.createElement(s.localName);
-          // Add reference of the moved element.
-          placeholder['__appliedElement'] = s;
-          // Disable this from appearing in document.styleSheets.
-          placeholder.setAttribute('type', 'import-placeholder');
-          // Append placeholder next to the sibling, and move original to <head>.
-          s.parentNode.insertBefore(placeholder, s.nextSibling);
-          let newSibling = importForElement(s);
-          while (newSibling && importForElement(newSibling)) {
-            newSibling = importForElement(newSibling);
-          }
-          if (newSibling.parentNode !== document.head) {
-            newSibling = null;
-          }
-          document.head.insertBefore(s, newSibling);
-          // Enable the loading of <link rel=stylesheet>.
-          s.removeAttribute('type');
-        }
-      }
-    }
-
-    /**
-     * Fires load/error events for imports in the right order .
-     */
-    fireEvents() {
-      const n$ = /** @type {!NodeList<!HTMLLinkElement>} */
-        (document.querySelectorAll(importSelector));
-      // Inverse order to have events firing bottom-up.
-      for (let i = n$.length - 1, n; i >= 0 && (n = n$[i]); i--) {
-        this.fireEventIfNeeded(n);
-      }
-    }
-
-    /**
-     * Fires load/error event for the import if this wasn't done already.
-     * @param {!HTMLLinkElement} link
-     */
-    fireEventIfNeeded(link) {
-      // Don't fire twice same event.
-      if (!link['__loaded']) {
-        link['__loaded'] = true;
-        // Update link's import readyState.
-        link.import && (link.import.readyState = 'complete');
-        const eventType = link.import ? 'load' : 'error';
-        link.dispatchEvent(newCustomEvent(eventType, {
-          bubbles: false,
-          cancelable: false,
-          detail: undefined
-        }));
-      }
-    }
-
-    /**
-     * @param {Array<MutationRecord>} mutations
-     */
-    handleMutations(mutations) {
-      for (let i = 0; i < mutations.length; i++) {
-        const m = mutations[i];
-        if (!m.addedNodes) {
-          continue;
-        }
-        for (let ii = 0; ii < m.addedNodes.length; ii++) {
-          const elem = m.addedNodes[ii];
-          if (!elem || elem.nodeType !== Node.ELEMENT_NODE) {
-            continue;
-          }
-          // NOTE: added scripts are not updating currentScript in IE.
-          if (isImportLink(elem)) {
-            this.loadImport( /** @type {!HTMLLinkElement} */ (elem));
-          } else {
-            this.loadImports( /** @type {!Element} */ (elem));
-          }
-        }
-      }
-    }
-  }
-
-  /**
-   * @param {!Node} node
-   * @return {boolean}
-   */
-  const isImportLink = node => {
-    return node.nodeType === Node.ELEMENT_NODE && node.localName === 'link' &&
-      ( /** @type {!HTMLLinkElement} */ (node).rel === 'import');
-  };
-
-  /**
-   * Waits for an element to finish loading. If already done loading, it will
-   * mark the element accordingly.
-   * @param {!(HTMLLinkElement|HTMLScriptElement|HTMLStyleElement)} element
-   * @param {function()=} callback
-   */
-  const whenElementLoaded = (element, callback) => {
-    if (element['__loaded']) {
-      callback && callback();
-    } else if (element.localName === 'script' && !element.src) {
-      // Inline scripts don't trigger load/error events, consider them already loaded.
-      element['__loaded'] = true;
-      callback && callback();
-    } else {
-      const onLoadingDone = event => {
-        element.removeEventListener(event.type, onLoadingDone);
-        element['__loaded'] = true;
-        callback && callback();
-      };
-      element.addEventListener('load', onLoadingDone);
-      // NOTE: We listen only for load events in IE/Edge, because in IE/Edge
-      // <style> with @import will fire error events for each failing @import,
-      // and finally will trigger the load event when all @import are
-      // finished (even if all fail).
-      if (!isIE || element.localName !== 'style') {
-        element.addEventListener('error', onLoadingDone);
-      }
-    }
-  };
-
-  /**
-   * Calls the callback when all imports in the document at call time
-   * (or at least document ready) have loaded. Callback is called synchronously
-   * if imports are already done loading.
-   * @param {function()=} callback
-   */
-  const whenReady = callback => {
-    // 1. ensure the document is in a ready state (has dom), then
-    // 2. watch for loading of imports and call callback when done
-    whenDocumentReady(() => whenImportsReady(() => callback && callback()));
-  };
-
-  /**
-   * Invokes the callback when document is in ready state. Callback is called
-   *  synchronously if document is already done loading.
-   * @param {!function()} callback
-   */
-  const whenDocumentReady = callback => {
-    if (document.readyState !== 'loading') {
-      callback();
-    } else {
-      const stateChanged = () => {
-        if (document.readyState !== 'loading') {
-          document.removeEventListener('readystatechange', stateChanged);
-          callback();
-        }
-      };
-      document.addEventListener('readystatechange', stateChanged);
-    }
-  };
-
-  /**
-   * Invokes the callback after all imports are loaded. Callback is called
-   * synchronously if imports are already done loading.
-   * @param {!function()} callback
-   */
-  const whenImportsReady = callback => {
-    let imports = /** @type {!NodeList<!HTMLLinkElement>} */
-      (document.querySelectorAll(rootImportSelector));
-    let pending = imports.length;
-    if (!pending) {
-      callback();
-      return;
-    }
-    for (let i = 0, l = imports.length, imp; i < l && (imp = imports[i]); i++) {
-      whenElementLoaded(imp, () => {
-        if (--pending === 0) {
-          callback();
-        }
-      });
-    }
-  };
-
-  /**
-   * Returns the import document containing the element.
-   * @param {!Node} element
-   * @return {HTMLLinkElement|Document|undefined}
-   */
-  const importForElement = element => {
-    if (useNative) {
-      // Return only if not in the main doc!
-      return element.ownerDocument !== document ? element.ownerDocument : null;
-    }
-    let doc = element['__importDoc'];
-    if (!doc && element.parentNode) {
-      doc = /** @type {!Element} */ (element.parentNode);
-      if (typeof doc.closest === 'function') {
-        // Element.closest returns the element itself if it matches the selector,
-        // so we search the closest import starting from the parent.
-        doc = doc.closest(importSelector);
-      } else {
-        // Walk up the parent tree until we find an import.
-        while (!isImportLink(doc) && (doc = doc.parentNode)) {}
-      }
-      element['__importDoc'] = doc;
-    }
-    return doc;
-  };
-
-  const newCustomEvent = (type, params) => {
-    if (typeof window.CustomEvent === 'function') {
-      return new CustomEvent(type, params);
-    }
-    const event = /** @type {!CustomEvent} */ (document.createEvent('CustomEvent'));
-    event.initCustomEvent(type, Boolean(params.bubbles), Boolean(params.cancelable), params.detail);
-    return event;
-  };
-
-  if (useNative) {
-    // Check for imports that might already be done loading by the time this
-    // script is actually executed. Native imports are blocking, so the ones
-    // available in the document by this time should already have failed
-    // or have .import defined.
-    const imps = /** @type {!NodeList<!HTMLLinkElement>} */
-      (document.querySelectorAll(importSelector));
-    for (let i = 0, l = imps.length, imp; i < l && (imp = imps[i]); i++) {
-      if (!imp.import || imp.import.readyState !== 'loading') {
-        imp['__loaded'] = true;
-      }
-    }
-    // Listen for load/error events to capture dynamically added scripts.
-    /**
-     * @type {!function(!Event)}
-     */
-    const onLoadingDone = event => {
-      const elem = /** @type {!Element} */ (event.target);
-      if (isImportLink(elem)) {
-        elem['__loaded'] = true;
-      }
-    };
-    document.addEventListener('load', onLoadingDone, true /* useCapture */ );
-    document.addEventListener('error', onLoadingDone, true /* useCapture */ );
-  } else {
-    new Importer();
-  }
-
-  /**
-    Add support for the `HTMLImportsLoaded` event and the `HTMLImports.whenReady`
-    method. This api is necessary because unlike the native implementation,
-    script elements do not force imports to resolve. Instead, users should wrap
-    code in either an `HTMLImportsLoaded` handler or after load time in an
-    `HTMLImports.whenReady(callback)` call.
-
-    NOTE: This module also supports these apis under the native implementation.
-    Therefore, if this file is loaded, the same code can be used under both
-    the polyfill and native implementation.
-   */
-  whenReady(() => document.dispatchEvent(newCustomEvent('HTMLImportsLoaded', {
-    cancelable: true,
-    bubbles: true,
-    detail: undefined
-  })));
-
-  // exports
-  scope.useNative = useNative;
-  scope.whenReady = whenReady;
-  scope.importForElement = importForElement;
-
-})(window.HTMLImports = (window.HTMLImports || {}));
-
-/**
- * @license
- * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
- * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
- * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
- * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
- * Code distributed by Google as part of the polymer project is also
- * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
- */
-
-(function() {
-
-  'use strict';
-
-  // Establish scope.
-  window['WebComponents'] = window['WebComponents'] || {'flags':{}};
-
-  // loading script
-  var file = 'webcomponents-lite.js';
-  var script = document.querySelector('script[src*="' + file + '"]');
-  var flagMatcher = /wc-(.+)/;
-
-  // Flags. Convert url arguments to flags
-  var flags = {};
-  if (!flags['noOpts']) {
-    // from url
-    location.search.slice(1).split('&').forEach(function(option) {
-      var parts = option.split('=');
-      var match;
-      if (parts[0] && (match = parts[0].match(flagMatcher))) {
-        flags[match[1]] = parts[1] || true;
-      }
-    });
-    // from script
-    if (script) {
-      for (var i=0, a; (a=script.attributes[i]); i++) {
-        if (a.name !== 'src') {
-          flags[a.name] = a.value || true;
-        }
-      }
-    }
-    // log flags
-    if (flags['log'] && flags['log']['split']) {
-      var parts = flags['log'].split(',');
-      flags['log'] = {};
-      parts.forEach(function(f) {
-        flags['log'][f] = true;
-      });
-    } else {
-      flags['log'] = {};
-    }
-  }
-
-  // exports
-  window['WebComponents']['flags'] = flags;
-  var forceShady = flags['shadydom'];
-  if (forceShady) {
-    window['ShadyDOM'] = window['ShadyDOM'] || {};
-    window['ShadyDOM']['force'] = forceShady;
-  }
-
-  var forceCE = flags['register'] || flags['ce'];
-  if (forceCE && window['customElements']) {
-    window['customElements']['forcePolyfill'] = forceCE;
-  }
-
-})();
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-let settings = window['ShadyDOM'] || {};
-
-settings.hasNativeShadowDOM = Boolean(Element.prototype.attachShadow && Node.prototype.getRootNode);
-
-let desc = Object.getOwnPropertyDescriptor(Node.prototype, 'firstChild');
-
-settings.hasDescriptors = Boolean(desc && desc.configurable && desc.get);
-settings.inUse = settings['force'] || !settings.hasNativeShadowDOM;
-
-function isShadyRoot(obj) {
-  return Boolean(obj.__localName === 'ShadyRoot');
-}
-
-function ownerShadyRootForNode(node) {
-  let root = node.getRootNode();
-  if (isShadyRoot(root)) {
-    return root;
-  }
-}
-
-let p = Element.prototype;
-let matches = p.matches || p.matchesSelector ||
-  p.mozMatchesSelector || p.msMatchesSelector ||
-  p.oMatchesSelector || p.webkitMatchesSelector;
-
-function matchesSelector(element, selector) {
-  return matches.call(element, selector);
-}
-
-function copyOwnProperty(name, source, target) {
-  let pd = Object.getOwnPropertyDescriptor(source, name);
-  if (pd) {
-    Object.defineProperty(target, name, pd);
-  }
-}
-
-function extend(target, source) {
-  if (target && source) {
-    let n$ = Object.getOwnPropertyNames(source);
-    for (let i=0, n; (i<n$.length) && (n=n$[i]); i++) {
-      copyOwnProperty(n, source, target);
-    }
-  }
-  return target || source;
-}
-
-function extendAll(target, ...sources) {
-  for (let i=0; i < sources.length; i++) {
-    extend(target, sources[i]);
-  }
-  return target;
-}
-
-function mixin(target, source) {
-  for (var i in source) {
-    target[i] = source[i];
-  }
-  return target;
-}
-
-function patchPrototype(obj, mixin) {
-  let proto = Object.getPrototypeOf(obj);
-  if (!proto.hasOwnProperty('__patchProto')) {
-    let patchProto = Object.create(proto);
-    patchProto.__sourceProto = proto;
-    extend(patchProto, mixin);
-    proto['__patchProto'] = patchProto;
-  }
-  // old browsers don't have setPrototypeOf
-  obj.__proto__ = proto['__patchProto'];
-}
-
-
-let twiddle = document.createTextNode('');
-let content = 0;
-let queue = [];
-new MutationObserver(() => {
-  while (queue.length) {
-    // catch errors in user code...
-    try {
-      queue.shift()();
-    } catch(e) {
-      // enqueue another record and throw
-      twiddle.textContent = content++;
-      throw(e);
-    }
-  }
-}).observe(twiddle, {characterData: true});
-
-// use MutationObserver to get microtask async timing.
-function microtask(callback) {
-  queue.push(callback);
-  twiddle.textContent = content++;
-}
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-// render enqueuer/flusher
-let flushList = [];
-let scheduled;
-function enqueue(callback) {
-  if (!scheduled) {
-    scheduled = true;
-    microtask(flush);
-  }
-  flushList.push(callback);
-}
-
-function flush() {
-  scheduled = false;
-  let didFlush = Boolean(flushList.length);
-  while (flushList.length) {
-    flushList.shift()();
-  }
-  return didFlush;
-}
-
-flush['list'] = flushList;
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-class AsyncObserver {
-
-  constructor() {
-    this._scheduled = false;
-    this.addedNodes = [];
-    this.removedNodes = [];
-    this.callbacks = new Set();
-  }
-
-  schedule() {
-    if (!this._scheduled) {
-      this._scheduled = true;
-      microtask(() => {
-        this.flush();
-      });
-    }
-  }
-
-  flush() {
-    if (this._scheduled) {
-      this._scheduled = false;
-      let mutations = this.takeRecords();
-      if (mutations.length) {
-        this.callbacks.forEach(function(cb) {
-          cb(mutations);
-        });
-      }
-    }
-  }
-
-  takeRecords() {
-    if (this.addedNodes.length || this.removedNodes.length) {
-      let mutations = [{
-        addedNodes: this.addedNodes,
-        removedNodes: this.removedNodes
-      }];
-      this.addedNodes = [];
-      this.removedNodes = [];
-      return mutations;
-    }
-    return [];
-  }
-
-}
-
-// TODO(sorvell): consider instead polyfilling MutationObserver
-// directly so that users do not have to fork their code.
-// Supporting the entire api may be challenging: e.g. filtering out
-// removed nodes in the wrong scope and seeing non-distributing
-// subtree child mutations.
-let observeChildren = function(node, callback) {
-  node.__shady = node.__shady || {};
-  if (!node.__shady.observer) {
-    node.__shady.observer = new AsyncObserver();
-  }
-  node.__shady.observer.callbacks.add(callback);
-  let observer = node.__shady.observer;
-  return {
-    _callback: callback,
-    _observer: observer,
-    _node: node,
-    takeRecords() {
-      return observer.takeRecords()
-    }
-  };
-};
-
-let unobserveChildren = function(handle) {
-  let observer = handle && handle._observer;
-  if (observer) {
-    observer.callbacks.delete(handle._callback);
-    if (!observer.callbacks.size) {
-      handle._node.__shady.observer = null;
-    }
-  }
-};
-
-function filterMutations(mutations, target) {
-  /** @const {Node} */
-  const targetRootNode = target.getRootNode();
-  return mutations.map(function(mutation) {
-    /** @const {boolean} */
-    const mutationInScope = (targetRootNode === mutation.target.getRootNode());
-    if (mutationInScope && mutation.addedNodes) {
-      let nodes = Array.from(mutation.addedNodes).filter(function(n) {
-        return (targetRootNode === n.getRootNode());
-      });
-      if (nodes.length) {
-        mutation = Object.create(mutation);
-        Object.defineProperty(mutation, 'addedNodes', {
-          value: nodes,
-          configurable: true
-        });
-        return mutation;
-      }
-    } else if (mutationInScope) {
-      return mutation;
-    }
-  }).filter(function(m) { return m});
-}
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-let appendChild = Element.prototype.appendChild;
-let insertBefore = Element.prototype.insertBefore;
-let removeChild = Element.prototype.removeChild;
-let setAttribute = Element.prototype.setAttribute;
-let removeAttribute = Element.prototype.removeAttribute;
-let cloneNode = Element.prototype.cloneNode;
-let importNode = Document.prototype.importNode;
-let addEventListener = Element.prototype.addEventListener;
-let removeEventListener = Element.prototype.removeEventListener;
-
-
-var nativeMethods = Object.freeze({
-	appendChild: appendChild,
-	insertBefore: insertBefore,
-	removeChild: removeChild,
-	setAttribute: setAttribute,
-	removeAttribute: removeAttribute,
-	cloneNode: cloneNode,
-	importNode: importNode,
-	addEventListener: addEventListener,
-	removeEventListener: removeEventListener
-});
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-// Cribbed from ShadowDOM polyfill
-// https://github.com/webcomponents/webcomponentsjs/blob/master/src/ShadowDOM/wrappers/HTMLElement.js#L28
-/////////////////////////////////////////////////////////////////////////////
-// innerHTML and outerHTML
-
-// http://www.whatwg.org/specs/web-apps/current-work/multipage/the-end.html#escapingString
-let escapeAttrRegExp = /[&\u00A0"]/g;
-let escapeDataRegExp = /[&\u00A0<>]/g;
-
-function escapeReplace(c) {
-  switch (c) {
-    case '&':
-      return '&amp;';
-    case '<':
-      return '&lt;';
-    case '>':
-      return '&gt;';
-    case '"':
-      return '&quot;';
-    case '\u00A0':
-      return '&nbsp;';
-  }
-}
-
-function escapeAttr(s) {
-  return s.replace(escapeAttrRegExp, escapeReplace);
-}
-
-function escapeData(s) {
-  return s.replace(escapeDataRegExp, escapeReplace);
-}
-
-function makeSet(arr) {
-  let set = {};
-  for (let i = 0; i < arr.length; i++) {
-    set[arr[i]] = true;
-  }
-  return set;
-}
-
-// http://www.whatwg.org/specs/web-apps/current-work/#void-elements
-let voidElements = makeSet([
-  'area',
-  'base',
-  'br',
-  'col',
-  'command',
-  'embed',
-  'hr',
-  'img',
-  'input',
-  'keygen',
-  'link',
-  'meta',
-  'param',
-  'source',
-  'track',
-  'wbr'
-]);
-
-let plaintextParents = makeSet([
-  'style',
-  'script',
-  'xmp',
-  'iframe',
-  'noembed',
-  'noframes',
-  'plaintext',
-  'noscript'
-]);
-
-/**
- * @param {Node} node
- * @param {Node} parentNode
- * @param {Function=} callback
- */
-function getOuterHTML(node, parentNode, callback) {
-  switch (node.nodeType) {
-    case Node.ELEMENT_NODE: {
-      let tagName = node.localName;
-      let s = '<' + tagName;
-      let attrs = node.attributes;
-      for (let i = 0, attr; (attr = attrs[i]); i++) {
-        s += ' ' + attr.name + '="' + escapeAttr(attr.value) + '"';
-      }
-      s += '>';
-      if (voidElements[tagName]) {
-        return s;
-      }
-      return s + getInnerHTML(node, callback) + '</' + tagName + '>';
-    }
-    case Node.TEXT_NODE: {
-      let data = /** @type {Text} */ (node).data;
-      if (parentNode && plaintextParents[parentNode.localName]) {
-        return data;
-      }
-      return escapeData(data);
-    }
-    case Node.COMMENT_NODE: {
-      return '<!--' + /** @type {Comment} */ (node).data + '-->';
-    }
-    default: {
-      window.console.error(node);
-      throw new Error('not implemented');
-    }
-  }
-}
-
-/**
- * @param {Node} node
- * @param {Function=} callback
- */
-function getInnerHTML(node, callback) {
-  if (node.localName === 'template') {
-    node =  /** @type {HTMLTemplateElement} */ (node).content;
-  }
-  let s = '';
-  let c$ = callback ? callback(node) : node.childNodes;
-  for (let i=0, l=c$.length, child; (i<l) && (child=c$[i]); i++) {
-    s += getOuterHTML(child, node, callback);
-  }
-  return s;
-}
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-let nodeWalker = document.createTreeWalker(document, NodeFilter.SHOW_ALL,
-  null, false);
-
-let elementWalker = document.createTreeWalker(document, NodeFilter.SHOW_ELEMENT,
-  null, false);
-
-function parentNode(node) {
-  nodeWalker.currentNode = node;
-  return nodeWalker.parentNode();
-}
-
-function firstChild(node) {
-  nodeWalker.currentNode = node;
-  return nodeWalker.firstChild();
-}
-
-function lastChild(node) {
-  nodeWalker.currentNode = node;
-  return nodeWalker.lastChild();
-}
-
-function previousSibling(node) {
-  nodeWalker.currentNode = node;
-  return nodeWalker.previousSibling();
-}
-
-function nextSibling(node) {
-  nodeWalker.currentNode = node;
-  return nodeWalker.nextSibling();
-}
-
-function childNodes(node) {
-  let nodes = [];
-  nodeWalker.currentNode = node;
-  let n = nodeWalker.firstChild();
-  while (n) {
-    nodes.push(n);
-    n = nodeWalker.nextSibling();
-  }
-  return nodes;
-}
-
-function parentElement(node) {
-  elementWalker.currentNode = node;
-  return elementWalker.parentNode();
-}
-
-function firstElementChild(node) {
-  elementWalker.currentNode = node;
-  return elementWalker.firstChild();
-}
-
-function lastElementChild(node) {
-  elementWalker.currentNode = node;
-  return elementWalker.lastChild();
-}
-
-function previousElementSibling(node) {
-  elementWalker.currentNode = node;
-  return elementWalker.previousSibling();
-}
-
-function nextElementSibling(node) {
-  elementWalker.currentNode = node;
-  return elementWalker.nextSibling();
-}
-
-function children(node) {
-  let nodes = [];
-  elementWalker.currentNode = node;
-  let n = elementWalker.firstChild();
-  while (n) {
-    nodes.push(n);
-    n = elementWalker.nextSibling();
-  }
-  return nodes;
-}
-
-function innerHTML(node) {
-  return getInnerHTML(node, (n) => childNodes(n));
-}
-
-function textContent(node) {
-  if (node.nodeType !== Node.ELEMENT_NODE) {
-    return node.nodeValue;
-  }
-  let textWalker = document.createTreeWalker(node, NodeFilter.SHOW_TEXT,
-    null, false);
-  let content = '', n;
-  while ( (n = textWalker.nextNode()) ) {
-    // TODO(sorvell): can't use textContent since we patch it on Node.prototype!
-    // However, should probably patch it only on element.
-    content += n.nodeValue;
-  }
-  return content;
-}
-
-var nativeTree = Object.freeze({
-	parentNode: parentNode,
-	firstChild: firstChild,
-	lastChild: lastChild,
-	previousSibling: previousSibling,
-	nextSibling: nextSibling,
-	childNodes: childNodes,
-	parentElement: parentElement,
-	firstElementChild: firstElementChild,
-	lastElementChild: lastElementChild,
-	previousElementSibling: previousElementSibling,
-	nextElementSibling: nextElementSibling,
-	children: children,
-	innerHTML: innerHTML,
-	textContent: textContent
-});
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-function clearNode(node) {
-  while (node.firstChild) {
-    node.removeChild(node.firstChild);
-  }
-}
-
-const nativeInnerHTMLDesc = /** @type {ObjectPropertyDescriptor} */(
-  Object.getOwnPropertyDescriptor(Element.prototype, 'innerHTML') ||
-  Object.getOwnPropertyDescriptor(HTMLElement.prototype, 'innerHTML'));
-
-const inertDoc = document.implementation.createHTMLDocument('inert');
-const htmlContainer = inertDoc.createElement('div');
-
-const nativeActiveElementDescriptor =
-  /** @type {ObjectPropertyDescriptor} */(
-    Object.getOwnPropertyDescriptor(Document.prototype, 'activeElement')
-  );
-function getDocumentActiveElement() {
-  if (nativeActiveElementDescriptor && nativeActiveElementDescriptor.get) {
-    return nativeActiveElementDescriptor.get.call(document);
-  } else if (!settings.hasDescriptors) {
-    return document.activeElement;
-  }
-}
-
-function activeElementForNode(node) {
-  let active = getDocumentActiveElement();
-  // In IE11, activeElement might be an empty object if the document is
-  // contained in an iframe.
-  // https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/10998788/
-  if (!active || !active.nodeType) {
-    return null;
-  }
-  let isShadyRoot$$1 = !!(isShadyRoot(node));
-  if (node !== document) {
-    // If this node isn't a document or shady root, then it doesn't have
-    // an active element.
-    if (!isShadyRoot$$1) {
-      return null;
-    }
-    // If this shady root's host is the active element or the active
-    // element is not a descendant of the host (in the composed tree),
-    // then it doesn't have an active element.
-    if (node.host === active ||
-        !node.host.contains(active)) {
-      return null;
-    }
-  }
-  // This node is either the document or a shady root of which the active
-  // element is a (composed) descendant of its host; iterate upwards to
-  // find the active element's most shallow host within it.
-  let activeRoot = ownerShadyRootForNode(active);
-  while (activeRoot && activeRoot !== node) {
-    active = activeRoot.host;
-    activeRoot = ownerShadyRootForNode(active);
-  }
-  if (node === document) {
-    // This node is the document, so activeRoot should be null.
-    return activeRoot ? null : active;
-  } else {
-    // This node is a non-document shady root, and it should be
-    // activeRoot.
-    return activeRoot === node ? active : null;
-  }
-}
-
-let OutsideAccessors = {
-
-  parentElement: {
-    /** @this {Node} */
-    get() {
-      let l = this.__shady && this.__shady.parentElement;
-      return l !== undefined ? l : parentElement(this);
-    },
-    configurable: true
-  },
-
-  parentNode: {
-    /** @this {Node} */
-    get() {
-      let l = this.__shady && this.__shady.parentNode;
-      return l !== undefined ? l : parentNode(this);
-    },
-    configurable: true
-  },
-
-  nextSibling: {
-    /** @this {Node} */
-    get() {
-      let l = this.__shady && this.__shady.nextSibling;
-      return l !== undefined ? l : nextSibling(this);
-    },
-    configurable: true
-  },
-
-  previousSibling: {
-    /** @this {Node} */
-    get() {
-      let l = this.__shady && this.__shady.previousSibling;
-      return l !== undefined ? l : previousSibling(this);
-    },
-    configurable: true
-  },
-
-  className: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      return this.getAttribute('class');
-    },
-    /**
-     * @this {HTMLElement}
-     */
-    set(value) {
-      this.setAttribute('class', value);
-    },
-    configurable: true
-  },
-
-  // fragment, element, document
-  nextElementSibling: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      if (this.__shady && this.__shady.nextSibling !== undefined) {
-        let n = this.nextSibling;
-        while (n && n.nodeType !== Node.ELEMENT_NODE) {
-          n = n.nextSibling;
-        }
-        return n;
-      } else {
-        return nextElementSibling(this);
-      }
-    },
-    configurable: true
-  },
-
-  previousElementSibling: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      if (this.__shady && this.__shady.previousSibling !== undefined) {
-        let n = this.previousSibling;
-        while (n && n.nodeType !== Node.ELEMENT_NODE) {
-          n = n.previousSibling;
-        }
-        return n;
-      } else {
-        return previousElementSibling(this);
-      }
-    },
-    configurable: true
-  }
-
-};
-
-let InsideAccessors = {
-
-  childNodes: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      if (this.__shady && this.__shady.firstChild !== undefined) {
-        if (!this.__shady.childNodes) {
-          this.__shady.childNodes = [];
-          for (let n=this.firstChild; n; n=n.nextSibling) {
-            this.__shady.childNodes.push(n);
-          }
-        }
-        return this.__shady.childNodes;
-      } else {
-        return childNodes(this);
-      }
-    },
-    configurable: true
-  },
-
-  firstChild: {
-    /** @this {HTMLElement} */
-    get() {
-      let l = this.__shady && this.__shady.firstChild;
-      return l !== undefined ? l : firstChild(this);
-    },
-    configurable: true
-  },
-
-  lastChild: {
-  /** @this {HTMLElement} */
-    get() {
-      let l = this.__shady && this.__shady.lastChild;
-      return l !== undefined ? l : lastChild(this);
-    },
-    configurable: true
-  },
-
-  textContent: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      if (this.__shady && this.__shady.firstChild !== undefined) {
-        let tc = [];
-        for (let i = 0, cn = this.childNodes, c; (c = cn[i]); i++) {
-          if (c.nodeType !== Node.COMMENT_NODE) {
-            tc.push(c.textContent);
-          }
-        }
-        return tc.join('');
-      } else {
-        return textContent(this);
-      }
-    },
-    /**
-     * @this {HTMLElement}
-     */
-    set(text) {
-      if (this.nodeType !== Node.ELEMENT_NODE) {
-        // TODO(sorvell): can't do this if patch nodeValue.
-        this.nodeValue = text;
-      } else {
-        clearNode(this);
-        if (text) {
-          this.appendChild(document.createTextNode(text));
-        }
-      }
-    },
-    configurable: true
-  },
-
-  // fragment, element, document
-  firstElementChild: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      if (this.__shady && this.__shady.firstChild !== undefined) {
-        let n = this.firstChild;
-        while (n && n.nodeType !== Node.ELEMENT_NODE) {
-          n = n.nextSibling;
-        }
-        return n;
-      } else {
-        return firstElementChild(this);
-      }
-    },
-    configurable: true
-  },
-
-  lastElementChild: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      if (this.__shady && this.__shady.lastChild !== undefined) {
-        let n = this.lastChild;
-        while (n && n.nodeType !== Node.ELEMENT_NODE) {
-          n = n.previousSibling;
-        }
-        return n;
-      } else {
-        return lastElementChild(this);
-      }
-    },
-    configurable: true
-  },
-
-  children: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      if (this.__shady && this.__shady.firstChild !== undefined) {
-        return Array.prototype.filter.call(this.childNodes, function(n) {
-          return (n.nodeType === Node.ELEMENT_NODE);
-        });
-      } else {
-        return children(this);
-      }
-    },
-    configurable: true
-  },
-
-  // element (HTMLElement on IE11)
-  innerHTML: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      let content = this.localName === 'template' ?
-        /** @type {HTMLTemplateElement} */(this).content : this;
-      if (this.__shady && this.__shady.firstChild !== undefined) {
-        return getInnerHTML(content);
-      } else {
-        return innerHTML(content);
-      }
-    },
-    /**
-     * @this {HTMLElement}
-     */
-    set(text) {
-      let content = this.localName === 'template' ?
-        /** @type {HTMLTemplateElement} */(this).content : this;
-      clearNode(content);
-      if (nativeInnerHTMLDesc && nativeInnerHTMLDesc.set) {
-        nativeInnerHTMLDesc.set.call(htmlContainer, text);
-      } else {
-        htmlContainer.innerHTML = text;
-      }
-      while (htmlContainer.firstChild) {
-        content.appendChild(htmlContainer.firstChild);
-      }
-    },
-    configurable: true
-  }
-
-};
-
-// Note: Can be patched on element prototype on all browsers.
-// Must be patched on instance on browsers that support native Shadow DOM
-// but do not have builtin accessors (old Chrome).
-let ShadowRootAccessor = {
-
-  shadowRoot: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      return this.__shady && this.__shady.root || null;
-    },
-    /**
-     * @this {HTMLElement}
-     */
-    set(value) {
-      this.__shady = this.__shady || {};
-      this.__shady.root = value;
-    },
-    configurable: true
-  }
-};
-
-// Note: Can be patched on document prototype on browsers with builtin accessors.
-// Must be patched separately on simulated ShadowRoot.
-// Must be patched as `_activeElement` on browsers without builtin accessors.
-let ActiveElementAccessor = {
-
-  activeElement: {
-    /**
-     * @this {HTMLElement}
-     */
-    get() {
-      return activeElementForNode(this);
-    },
-    /**
-     * @this {HTMLElement}
-     */
-    set() {},
-    configurable: true
-  }
-
-};
-
-// patch a group of descriptors on an object only if it exists or if the `force`
-// argument is true.
-/**
- * @param {!Object} obj
- * @param {!Object} descriptors
- * @param {boolean=} force
- */
-function patchAccessorGroup(obj, descriptors, force) {
-  for (let p in descriptors) {
-    let objDesc = Object.getOwnPropertyDescriptor(obj, p);
-    if ((objDesc && objDesc.configurable) ||
-      (!objDesc && force)) {
-      Object.defineProperty(obj, p, descriptors[p]);
-    } else if (force) {
-      console.warn('Could not define', p, 'on', obj);
-    }
-  }
-}
-
-// patch dom accessors on proto where they exist
-function patchAccessors(proto) {
-  patchAccessorGroup(proto, OutsideAccessors);
-  patchAccessorGroup(proto, InsideAccessors);
-  patchAccessorGroup(proto, ActiveElementAccessor);
-}
-
-// ensure element descriptors (IE/Edge don't have em)
-function patchShadowRootAccessors(proto) {
-  patchAccessorGroup(proto, InsideAccessors, true);
-  patchAccessorGroup(proto, ActiveElementAccessor, true);
-}
-
-// ensure an element has patched "outside" accessors; no-op when not needed
-let patchOutsideElementAccessors = settings.hasDescriptors ?
-  function() {} : function(element) {
-    if (!(element.__shady && element.__shady.__outsideAccessors)) {
-      element.__shady = element.__shady || {};
-      element.__shady.__outsideAccessors = true;
-      patchAccessorGroup(element, OutsideAccessors, true);
-    }
-  };
-
-// ensure an element has patched "inside" accessors; no-op when not needed
-let patchInsideElementAccessors = settings.hasDescriptors ?
-  function() {} : function(element) {
-    if (!(element.__shady && element.__shady.__insideAccessors)) {
-      element.__shady = element.__shady || {};
-      element.__shady.__insideAccessors = true;
-      patchAccessorGroup(element, InsideAccessors, true);
-      patchAccessorGroup(element, ShadowRootAccessor, true);
-    }
-  };
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-function recordInsertBefore(node, container, ref_node) {
-  patchInsideElementAccessors(container);
-  container.__shady = container.__shady || {};
-  if (container.__shady.firstChild !== undefined) {
-    container.__shady.childNodes = null;
-  }
-  // handle document fragments
-  if (node.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
-    let c$ = node.childNodes;
-    for (let i=0; i < c$.length; i++) {
-      linkNode(c$[i], container, ref_node);
-    }
-    // cleanup logical dom in doc fragment.
-    node.__shady = node.__shady || {};
-    let resetTo = (node.__shady.firstChild !== undefined) ? null : undefined;
-    node.__shady.firstChild = node.__shady.lastChild = resetTo;
-    node.__shady.childNodes = resetTo;
-  } else {
-    linkNode(node, container, ref_node);
-  }
-}
-
-function linkNode(node, container, ref_node) {
-  patchOutsideElementAccessors(node);
-  ref_node = ref_node || null;
-  node.__shady = node.__shady || {};
-  container.__shady = container.__shady || {};
-  if (ref_node) {
-    ref_node.__shady = ref_node.__shady || {};
-  }
-  // update ref_node.previousSibling <-> node
-  node.__shady.previousSibling = ref_node ? ref_node.__shady.previousSibling :
-    container.lastChild;
-  let ps = node.__shady.previousSibling;
-  if (ps && ps.__shady) {
-    ps.__shady.nextSibling = node;
-  }
-  // update node <-> ref_node
-  let ns = node.__shady.nextSibling = ref_node;
-  if (ns && ns.__shady) {
-    ns.__shady.previousSibling = node;
-  }
-  // update node <-> container
-  node.__shady.parentNode = container;
-  if (ref_node) {
-    if (ref_node === container.__shady.firstChild) {
-      container.__shady.firstChild = node;
-    }
-  } else {
-    container.__shady.lastChild = node;
-    if (!container.__shady.firstChild) {
-      container.__shady.firstChild = node;
-    }
-  }
-  // remove caching of childNodes
-  container.__shady.childNodes = null;
-}
-
-function recordRemoveChild(node, container) {
-  node.__shady = node.__shady || {};
-  container.__shady = container.__shady || {};
-  if (node === container.__shady.firstChild) {
-    container.__shady.firstChild = node.__shady.nextSibling;
-  }
-  if (node === container.__shady.lastChild) {
-    container.__shady.lastChild = node.__shady.previousSibling;
-  }
-  let p = node.__shady.previousSibling;
-  let n = node.__shady.nextSibling;
-  if (p) {
-    p.__shady = p.__shady || {};
-    p.__shady.nextSibling = n;
-  }
-  if (n) {
-    n.__shady = n.__shady || {};
-    n.__shady.previousSibling = p;
-  }
-  // When an element is removed, logical data is no longer tracked.
-  // Explicitly set `undefined` here to indicate this. This is disginguished
-  // from `null` which is set if info is null.
-  node.__shady.parentNode = node.__shady.previousSibling =
-    node.__shady.nextSibling = undefined;
-  if (container.__shady.childNodes !== undefined) {
-    // remove caching of childNodes
-    container.__shady.childNodes = null;
-  }
-}
-
-let recordChildNodes = function(node) {
-  if (!node.__shady || node.__shady.firstChild === undefined) {
-    node.__shady = node.__shady || {};
-    node.__shady.firstChild = firstChild(node);
-    node.__shady.lastChild = lastChild(node);
-    patchInsideElementAccessors(node);
-    let c$ = node.__shady.childNodes = childNodes(node);
-    for (let i=0, n; (i<c$.length) && (n=c$[i]); i++) {
-      n.__shady = n.__shady || {};
-      n.__shady.parentNode = node;
-      n.__shady.nextSibling = c$[i+1] || null;
-      n.__shady.previousSibling = c$[i-1] || null;
-      patchOutsideElementAccessors(n);
-    }
-  }
-};
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/**
- * Try to add node. Record logical info, track insertion points, perform
- * distribution iff needed. Return true if the add is handled.
- * @param {Node} container
- * @param {Node} node
- * @param {Node} ref_node
- * @return {boolean}
- */
-function addNode(container, node, ref_node) {
-  let ownerRoot = ownerShadyRootForNode(container);
-  let ipAdded;
-  if (ownerRoot) {
-    // optimization: special insertion point tracking
-    // TODO(sorvell): verify that the renderPending check here should not be needed.
-    if (node['__noInsertionPoint'] && !ownerRoot._changePending) {
-      ownerRoot._skipUpdateInsertionPoints = true;
-    }
-    // note: we always need to see if an insertion point is added
-    // since this saves logical tree info; however, invalidation state
-    // needs
-    ipAdded = _maybeAddInsertionPoint(node, container, ownerRoot);
-    // invalidate insertion points IFF not already invalid!
-    if (ipAdded) {
-      ownerRoot._skipUpdateInsertionPoints = false;
-    }
-  }
-  if (container.__shady && container.__shady.firstChild !== undefined) {
-    recordInsertBefore(node, container, ref_node);
-  }
-  // if not distributing and not adding to host, do a fast path addition
-  // TODO(sorvell): revisit flow since `ipAdded` needed here if
-  // node is a fragment that has a patched QSA.
-  let handled = _maybeDistribute(node, container, ownerRoot, ipAdded) ||
-    container.__shady.root ||
-    // TODO(sorvell): we *should* consider the add "handled"
-    // if the container or ownerRoot is `_renderPending`.
-    // However, this will regress performance right now and is blocked on a
-    // fix for https://github.com/webcomponents/shadydom/issues/95
-    // handled if ref_node parent is a root that is rendering.
-    (ref_node && isShadyRoot(ref_node.parentNode) &&
-      ref_node.parentNode._renderPending);
-  return handled;
-}
-
-
-/**
- * Try to remove node: update logical info and perform distribution iff
- * needed. Return true if the removal has been handled.
- * note that it's possible for both the node's host and its parent
- * to require distribution... both cases are handled here.
- * @param {Node} node
- * @return {boolean}
- */
-function removeNode(node) {
-  // important that we want to do this only if the node has a logical parent
-  let logicalParent = node.__shady && node.__shady.parentNode;
-  let distributed;
-  let ownerRoot = ownerShadyRootForNode(node);
-  if (logicalParent || ownerRoot) {
-    // distribute node's parent iff needed
-    distributed = maybeDistributeParent(node);
-    if (logicalParent) {
-      recordRemoveChild(node, logicalParent);
-    }
-    // remove node from root and distribute it iff needed
-    let removedDistributed = ownerRoot &&
-      _removeDistributedChildren(ownerRoot, node);
-    let addedInsertionPoint = (logicalParent && ownerRoot &&
-      logicalParent.localName === ownerRoot.getInsertionPointTag());
-    if (removedDistributed || addedInsertionPoint) {
-      ownerRoot._skipUpdateInsertionPoints = false;
-      updateRootViaContentChange(ownerRoot);
-    }
-  }
-  _removeOwnerShadyRoot(node);
-  return distributed;
-}
-
-/**
- * @param {Node} node
- * @param {Node=} addedNode
- * @param {Node=} removedNode
- */
-function _scheduleObserver(node, addedNode, removedNode) {
-  let observer = node.__shady && node.__shady.observer;
-  if (observer) {
-    if (addedNode) {
-      observer.addedNodes.push(addedNode);
-    }
-    if (removedNode) {
-      observer.removedNodes.push(removedNode);
-    }
-    observer.schedule();
-  }
-}
-
-function removeNodeFromParent(node, logicalParent) {
-  if (logicalParent) {
-    _scheduleObserver(logicalParent, null, node);
-    return removeNode(node);
-  } else {
-    // composed but not logical parent
-    if (node.parentNode) {
-      removeChild.call(node.parentNode, node);
-    }
-    _removeOwnerShadyRoot(node);
-  }
-}
-
-function _hasCachedOwnerRoot(node) {
-  return Boolean(node.__shady && node.__shady.ownerShadyRoot !== undefined);
-}
-
-/**
- * @param {Node} node
- * @param {Object=} options
- */
-function getRootNode(node, options) { // eslint-disable-line no-unused-vars
-  if (!node || !node.nodeType) {
-    return;
-  }
-  node.__shady = node.__shady || {};
-  let root = node.__shady.ownerShadyRoot;
-  if (root === undefined) {
-    if (isShadyRoot(node)) {
-      root = node;
-    } else {
-      let parent = node.parentNode;
-      root = parent ? getRootNode(parent) : node;
-    }
-    // memo-ize result for performance but only memo-ize
-    // result if node is in the document. This avoids a problem where a root
-    // can be cached while an element is inside a fragment.
-    // If this happens and we cache the result, the value can become stale
-    // because for perf we avoid processing the subtree of added fragments.
-    if (document.documentElement.contains(node)) {
-      node.__shady.ownerShadyRoot = root;
-    }
-  }
-  return root;
-}
-
-function _maybeDistribute(node, container, ownerRoot, ipAdded) {
-  // TODO(sorvell): technically we should check non-fragment nodes for
-  // <content> children but since this case is assumed to be exceedingly
-  // rare, we avoid the cost and will address with some specific api
-  // when the need arises.  For now, the user must call
-  // distributeContent(true), which updates insertion points manually
-  // and forces distribution.
-  let insertionPointTag = ownerRoot && ownerRoot.getInsertionPointTag() || '';
-  let fragContent = (node.nodeType === Node.DOCUMENT_FRAGMENT_NODE) &&
-    !node['__noInsertionPoint'] &&
-    insertionPointTag && node.querySelector(insertionPointTag);
-  let wrappedContent = fragContent &&
-    (fragContent.parentNode.nodeType !==
-    Node.DOCUMENT_FRAGMENT_NODE);
-  let hasContent = fragContent || (node.localName === insertionPointTag);
-  // There are 3 possible cases where a distribution may need to occur:
-  // 1. <content> being inserted (the host of the shady root where
-  //    content is inserted needs distribution)
-  // 2. children being inserted into parent with a shady root (parent
-  //    needs distribution)
-  // 3. container is an insertionPoint
-  if (hasContent || (container.localName === insertionPointTag) || ipAdded) {
-    if (ownerRoot) {
-      // note, insertion point list update is handled after node
-      // mutations are complete
-      updateRootViaContentChange(ownerRoot);
-    }
-  }
-  let needsDist = _nodeNeedsDistribution(container);
-  if (needsDist) {
-    let root = container.__shady && container.__shady.root;
-    updateRootViaContentChange(root);
-  }
-  // Return true when distribution will fully handle the composition
-  // Note that if a content was being inserted that was wrapped by a node,
-  // and the parent does not need distribution, return false to allow
-  // the nodes to be added directly, after which children may be
-  // distributed and composed into the wrapping node(s)
-  return needsDist || (hasContent && !wrappedContent);
-}
-
-/* note: parent argument is required since node may have an out
-of date parent at this point; returns true if a <content> is being added */
-function _maybeAddInsertionPoint(node, parent, root) {
-  let added;
-  let insertionPointTag = root.getInsertionPointTag();
-  if (node.nodeType === Node.DOCUMENT_FRAGMENT_NODE &&
-    !node['__noInsertionPoint']) {
-    let c$ = node.querySelectorAll(insertionPointTag);
-    for (let i=0, n, np, na; (i<c$.length) && (n=c$[i]); i++) {
-      np = n.parentNode;
-      // don't allow node's parent to be fragment itself
-      if (np === node) {
-        np = parent;
-      }
-      na = _maybeAddInsertionPoint(n, np, root);
-      added = added || na;
-    }
-  } else if (node.localName === insertionPointTag) {
-    recordChildNodes(parent);
-    recordChildNodes(node);
-    added = true;
-  }
-  return added;
-}
-
-function _nodeNeedsDistribution(node) {
-  let root = node && node.__shady && node.__shady.root;
-  return root && root.hasInsertionPoint();
-}
-
-function _removeDistributedChildren(root, container) {
-  let hostNeedsDist;
-  let ip$ = root._getInsertionPoints();
-  for (let i=0; i<ip$.length; i++) {
-    let insertionPoint = ip$[i];
-    if (_contains(container, insertionPoint)) {
-      let dc$ = insertionPoint.assignedNodes({flatten: true});
-      for (let j=0; j<dc$.length; j++) {
-        hostNeedsDist = true;
-        let node = dc$[j];
-        let parent = parentNode(node);
-        if (parent) {
-          removeChild.call(parent, node);
-        }
-      }
-    }
-  }
-  return hostNeedsDist;
-}
-
-function _contains(container, node) {
-  while (node) {
-    if (node == container) {
-      return true;
-    }
-    node = node.parentNode;
-  }
-}
-
-function _removeOwnerShadyRoot(node) {
-  // optimization: only reset the tree if node is actually in a root
-  if (_hasCachedOwnerRoot(node)) {
-    let c$ = node.childNodes;
-    for (let i=0, l=c$.length, n; (i<l) && (n=c$[i]); i++) {
-      _removeOwnerShadyRoot(n);
-    }
-  }
-  node.__shady = node.__shady || {};
-  node.__shady.ownerShadyRoot = undefined;
-}
-
-// TODO(sorvell): This will fail if distribution that affects this
-// question is pending; this is expected to be exceedingly rare, but if
-// the issue comes up, we can force a flush in this case.
-function firstComposedNode(insertionPoint) {
-  let n$ = insertionPoint.assignedNodes({flatten: true});
-  let root = getRootNode(insertionPoint);
-  for (let i=0, l=n$.length, n; (i<l) && (n=n$[i]); i++) {
-    // means that we're composed to this spot.
-    if (root.isFinalDestination(insertionPoint, n)) {
-      return n;
-    }
-  }
-}
-
-function maybeDistributeParent(node) {
-  let parent = node.parentNode;
-  if (_nodeNeedsDistribution(parent)) {
-    updateRootViaContentChange(parent.__shady.root);
-    return true;
-  }
-}
-
-function updateRootViaContentChange(root) {
-  // mark root as mutation based on a mutation
-  root._changePending = true;
-  root.update();
-}
-
-function distributeAttributeChange(node, name) {
-  if (name === 'slot') {
-    maybeDistributeParent(node);
-  } else if (node.localName === 'slot' && name === 'name') {
-    let root = ownerShadyRootForNode(node);
-    if (root) {
-      root.update();
-    }
-  }
-}
-
-// NOTE: `query` is used primarily for ShadyDOM's querySelector impl,
-// but it's also generally useful to recurse through the element tree
-// and is used by Polymer's styling system.
-/**
- * @param {Node} node
- * @param {Function} matcher
- * @param {Function=} halter
- */
-function query(node, matcher, halter) {
-  let list = [];
-  _queryElements(node.childNodes, matcher,
-    halter, list);
-  return list;
-}
-
-function _queryElements(elements, matcher, halter, list) {
-  for (let i=0, l=elements.length, c; (i<l) && (c=elements[i]); i++) {
-    if (c.nodeType === Node.ELEMENT_NODE &&
-        _queryElement(c, matcher, halter, list)) {
-      return true;
-    }
-  }
-}
-
-function _queryElement(node, matcher, halter, list) {
-  let result = matcher(node);
-  if (result) {
-    list.push(node);
-  }
-  if (halter && halter(result)) {
-    return result;
-  }
-  _queryElements(node.childNodes, matcher,
-    halter, list);
-}
-
-function renderRootNode(element) {
-  var root = element.getRootNode();
-  if (isShadyRoot(root)) {
-    root.render();
-  }
-}
-
-let scopingShim = null;
-
-function setAttribute$1(node, attr, value) {
-  if (!scopingShim) {
-    scopingShim = window['ShadyCSS'] && window['ShadyCSS']['ScopingShim'];
-  }
-  if (scopingShim && attr === 'class') {
-    scopingShim['setElementClass'](node, value);
-  } else {
-    setAttribute.call(node, attr, value);
-    distributeAttributeChange(node, attr);
-  }
-}
-
-function removeAttribute$1(node, attr) {
-  removeAttribute.call(node, attr);
-  distributeAttributeChange(node, attr);
-}
-
-// cases in which we may not be able to just do standard native call
-// 1. container has a shadyRoot (needsDistribution IFF the shadyRoot
-// has an insertion point)
-// 2. container is a shadyRoot (don't distribute, instead set
-// container to container.host.
-// 3. node is <content> (host of container needs distribution)
-/**
- * @param {Node} parent
- * @param {Node} node
- * @param {Node=} ref_node
- */
-function insertBefore$1(parent, node, ref_node) {
-  if (ref_node) {
-    let p = ref_node.__shady && ref_node.__shady.parentNode;
-    if ((p !== undefined && p !== parent) ||
-      (p === undefined && parentNode(ref_node) !== parent)) {
-      throw Error(`Failed to execute 'insertBefore' on 'Node': The node ` +
-       `before which the new node is to be inserted is not a child of this node.`);
-    }
-  }
-  if (ref_node === node) {
-    return node;
-  }
-  // remove node from its current position iff it's in a tree.
-  if (node.nodeType !== Node.DOCUMENT_FRAGMENT_NODE) {
-    let parent = node.__shady && node.__shady.parentNode;
-    removeNodeFromParent(node, parent);
-  }
-  if (!addNode(parent, node, ref_node)) {
-    if (ref_node) {
-      // if ref_node is an insertion point replace with first distributed node
-      let root = ownerShadyRootForNode(ref_node);
-      if (root) {
-        ref_node = ref_node.localName === root.getInsertionPointTag() ?
-          firstComposedNode(/** @type {!HTMLSlotElement} */(ref_node)) : ref_node;
-      }
-    }
-    // if adding to a shadyRoot, add to host instead
-    let container = isShadyRoot(parent) ? /** @type {ShadowRoot} */(parent).host : parent;
-    if (ref_node) {
-      insertBefore.call(container, node, ref_node);
-    } else {
-      appendChild.call(container, node);
-    }
-  }
-  _scheduleObserver(parent, node);
-  return node;
-}
-
-/**
-  Removes the given `node` from the element's `lightChildren`.
-  This method also performs dom composition.
-*/
-function removeChild$1(parent, node) {
-  if (node.parentNode !== parent) {
-    throw Error('The node to be removed is not a child of this node: ' +
-      node);
-  }
-  if (!removeNode(node)) {
-    // if removing from a shadyRoot, remove form host instead
-    let container = isShadyRoot(parent) ?
-      parent.host :
-      parent;
-    // not guaranteed to physically be in container; e.g.
-    // undistributed nodes.
-    let nativeParent = parentNode(node);
-    if (container === nativeParent) {
-      removeChild.call(container, node);
-    }
-  }
-  _scheduleObserver(parent, null, node);
-  return node;
-}
-
-function cloneNode$1(node, deep) {
-  if (node.localName == 'template') {
-    return cloneNode.call(node, deep);
-  } else {
-    let n = cloneNode.call(node, false);
-    if (deep) {
-      let c$ = node.childNodes;
-      for (let i=0, nc; i < c$.length; i++) {
-        nc = c$[i].cloneNode(true);
-        n.appendChild(nc);
-      }
-    }
-    return n;
-  }
-}
-
-// note: Though not technically correct, we fast path `importNode`
-// when called on a node not owned by the main document.
-// This allows, for example, elements that cannot
-// contain custom elements and are therefore not likely to contain shadowRoots
-// to cloned natively. This is a fairly significant performance win.
-function importNode$1(node, deep) {
-  if (node.ownerDocument !== document) {
-    return importNode.call(document, node, deep);
-  }
-  let n = importNode.call(document, node, false);
-  if (deep) {
-    let c$ = node.childNodes;
-    for (let i=0, nc; i < c$.length; i++) {
-      nc = importNode$1(c$[i], true);
-      n.appendChild(nc);
-    }
-  }
-  return n;
-}
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-// https://github.com/w3c/webcomponents/issues/513#issuecomment-224183937
-let alwaysComposed = {
-  'focusin': true,
-  'focusout': true,
-  'click': true,
-  'dblclick': true,
-  'mousedown': true,
-  'mouseenter': true,
-  'mouseleave': true,
-  'mousemove': true,
-  'mouseout': true,
-  'mouseover': true,
-  'mouseup': true,
-  'wheel': true,
-  'beforeinput': true,
-  'input': true,
-  'keydown': true,
-  'keyup': true,
-  'compositionstart': true,
-  'compositionupdate': true,
-  'compositionend': true,
-  'touchstart': true,
-  'touchend': true,
-  'touchmove': true,
-  'touchcancel': true,
-  'pointerover': true,
-  'pointerenter': true,
-  'pointerdown': true,
-  'pointermove': true,
-  'pointerup': true,
-  'pointercancel': true,
-  'pointerout': true,
-  'pointerleave': true,
-  'gotpointercapture': true,
-  'lostpointercapture': true,
-  'dragstart': true,
-  'drag': true,
-  'dragenter': true,
-  'dragleave': true,
-  'dragover': true,
-  'drop': true,
-  'dragend': true,
-  'DOMActivate': true,
-  'DOMFocusIn': true,
-  'DOMFocusOut': true,
-  'keypress': true
-};
-
-function pathComposer(startNode, composed) {
-  let composedPath = [];
-  let current = startNode;
-  let startRoot = startNode === window ? window : startNode.getRootNode();
-  while (current) {
-    composedPath.push(current);
-    if (current.assignedSlot) {
-      current = current.assignedSlot;
-    } else if (current.nodeType === Node.DOCUMENT_FRAGMENT_NODE && current.host && (composed || current !== startRoot)) {
-      current = current.host;
-    } else {
-      current = current.parentNode;
-    }
-  }
-  // event composedPath includes window when startNode's ownerRoot is document
-  if (composedPath[composedPath.length - 1] === document) {
-    composedPath.push(window);
-  }
-  return composedPath;
-}
-
-function retarget(refNode, path) {
-  if (!isShadyRoot) {
-    return refNode;
-  }
-  // If ANCESTOR's root is not a shadow root or ANCESTOR's root is BASE's
-  // shadow-including inclusive ancestor, return ANCESTOR.
-  let refNodePath = pathComposer(refNode, true);
-  let p$ = path;
-  for (let i=0, ancestor, lastRoot, root, rootIdx; i < p$.length; i++) {
-    ancestor = p$[i];
-    root = ancestor === window ? window : ancestor.getRootNode();
-    if (root !== lastRoot) {
-      rootIdx = refNodePath.indexOf(root);
-      lastRoot = root;
-    }
-    if (!isShadyRoot(root) || rootIdx > -1) {
-      return ancestor;
-    }
-  }
-}
-
-let eventMixin = {
-
-  /**
-   * @this {Event}
-   */
-  get composed() {
-    // isTrusted may not exist in this browser, so just check if isTrusted is explicitly false
-    if (this.isTrusted !== false && this.__composed === undefined) {
-      this.__composed = alwaysComposed[this.type];
-    }
-    return this.__composed || false;
-  },
-
-  /**
-   * @this {Event}
-   */
-  composedPath() {
-    if (!this.__composedPath) {
-      this.__composedPath = pathComposer(this['__target'], this.composed);
-    }
-    return this.__composedPath;
-  },
-
-  /**
-   * @this {Event}
-   */
-  get target() {
-    return retarget(this.currentTarget, this.composedPath());
-  },
-
-  // http://w3c.github.io/webcomponents/spec/shadow/#event-relatedtarget-retargeting
-  /**
-   * @this {Event}
-   */
-  get relatedTarget() {
-    if (!this.__relatedTarget) {
-      return null;
-    }
-    if (!this.__relatedTargetComposedPath) {
-      this.__relatedTargetComposedPath = pathComposer(this.__relatedTarget, true);
-    }
-    // find the deepest node in relatedTarget composed path that is in the same root with the currentTarget
-    return retarget(this.currentTarget, this.__relatedTargetComposedPath);
-  },
-  /**
-   * @this {Event}
-   */
-  stopPropagation() {
-    Event.prototype.stopPropagation.call(this);
-    this.__propagationStopped = true;
-  },
-  /**
-   * @this {Event}
-   */
-  stopImmediatePropagation() {
-    Event.prototype.stopImmediatePropagation.call(this);
-    this.__immediatePropagationStopped = true;
-    this.__propagationStopped = true;
-  }
-
-};
-
-function mixinComposedFlag(Base) {
-  // NOTE: avoiding use of `class` here so that transpiled output does not
-  // try to do `Base.call` with a dom construtor.
-  let klazz = function(type, options) {
-    let event = new Base(type, options);
-    event.__composed = options && Boolean(options['composed']);
-    return event;
-  };
-  // put constructor properties on subclass
-  mixin(klazz, Base);
-  klazz.prototype = Base.prototype;
-  return klazz;
-}
-
-let nonBubblingEventsToRetarget = {
-  'focus': true,
-  'blur': true
-};
-
-
-function fireHandlers(event, node, phase) {
-  let hs = node.__handlers && node.__handlers[event.type] &&
-    node.__handlers[event.type][phase];
-  if (hs) {
-    for (let i = 0, fn; (fn = hs[i]); i++) {
-      fn.call(node, event);
-      if (event.__immediatePropagationStopped) {
-        return;
-      }
-    }
-  }
-}
-
-function retargetNonBubblingEvent(e) {
-  let path = e.composedPath();
-  let node;
-  // override `currentTarget` to let patched `target` calculate correctly
-  Object.defineProperty(e, 'currentTarget', {
-    get: function() {
-      return node;
-    },
-    configurable: true
-  });
-  for (let i = path.length - 1; i >= 0; i--) {
-    node = path[i];
-    // capture phase fires all capture handlers
-    fireHandlers(e, node, 'capture');
-    if (e.__propagationStopped) {
-      return;
-    }
-  }
-
-  // set the event phase to `AT_TARGET` as in spec
-  Object.defineProperty(e, 'eventPhase', {value: Event.AT_TARGET});
-
-  // the event only needs to be fired when owner roots change when iterating the event path
-  // keep track of the last seen owner root
-  let lastFiredRoot;
-  for (let i = 0; i < path.length; i++) {
-    node = path[i];
-    if (i === 0 || (node.shadowRoot && node.shadowRoot === lastFiredRoot)) {
-      fireHandlers(e, node, 'bubble');
-      // don't bother with window, it doesn't have `getRootNode` and will be last in the path anyway
-      if (node !== window) {
-        lastFiredRoot = node.getRootNode();
-      }
-      if (e.__propagationStopped) {
-        return;
-      }
-    }
-  }
-}
-
-/**
- * @this {Event}
- */
-function addEventListener$1(type, fn, optionsOrCapture) {
-  if (!fn) {
-    return;
-  }
-
-  // The callback `fn` might be used for multiple nodes/events. Since we generate
-  // a wrapper function, we need to keep track of it when we remove the listener.
-  // It's more efficient to store the node/type/options information as Array in
-  // `fn` itself rather than the node (we assume that the same callback is used
-  // for few nodes at most, whereas a node will likely have many event listeners).
-  // NOTE(valdrin) invoking external functions is costly, inline has better perf.
-  let capture, once, passive;
-  if (typeof optionsOrCapture === 'object') {
-    capture = Boolean(optionsOrCapture.capture);
-    once = Boolean(optionsOrCapture.once);
-    passive = Boolean(optionsOrCapture.passive);
-  } else {
-    capture = Boolean(optionsOrCapture);
-    once = false;
-    passive = false;
-  }
-  if (fn.__eventWrappers) {
-    // Stop if the wrapper function has already been created.
-    for (let i = 0; i < fn.__eventWrappers.length; i++) {
-      if (fn.__eventWrappers[i].node === this &&
-          fn.__eventWrappers[i].type === type &&
-          fn.__eventWrappers[i].capture === capture &&
-          fn.__eventWrappers[i].once === once &&
-          fn.__eventWrappers[i].passive === passive) {
-        return;
-      }
-    }
-  } else {
-    fn.__eventWrappers = [];
-  }
-
-  /**
-   * @this {HTMLElement}
-   */
-  const wrapperFn = function(e) {
-    // Support `once` option.
-    if (once) {
-      this.removeEventListener(type, fn, optionsOrCapture);
-    }
-    if (!e['__target']) {
-      patchEvent(e);
-    }
-    // There are two critera that should stop events from firing on this node
-    // 1. the event is not composed and the current node is not in the same root as the target
-    // 2. when bubbling, if after retargeting, relatedTarget and target point to the same node
-    if (e.composed || e.composedPath().indexOf(this) > -1) {
-      if (e.eventPhase === Event.BUBBLING_PHASE) {
-        if (e.target === e.relatedTarget) {
-          e.stopImmediatePropagation();
-          return;
-        }
-      }
-      return fn(e);
-    }
-  };
-  // Store the wrapper information.
-  fn.__eventWrappers.push({
-    node: this,
-    type: type,
-    capture: capture,
-    once: once,
-    passive: passive,
-    wrapperFn: wrapperFn
-  });
-
-  if (nonBubblingEventsToRetarget[type]) {
-    this.__handlers = this.__handlers || {};
-    this.__handlers[type] = this.__handlers[type] ||
-      {'capture': [], 'bubble': []};
-    this.__handlers[type][capture ? 'capture' : 'bubble'].push(wrapperFn);
-  } else {
-    addEventListener.call(this, type, wrapperFn, optionsOrCapture);
-  }
-}
-
-/**
- * @this {Event}
- */
-function removeEventListener$1(type, fn, optionsOrCapture) {
-  if (!fn) {
-    return;
-  }
-
-  // NOTE(valdrin) invoking external functions is costly, inline has better perf.
-  let capture, once, passive;
-  if (typeof optionsOrCapture === 'object') {
-    capture = Boolean(optionsOrCapture.capture);
-    once = Boolean(optionsOrCapture.once);
-    passive = Boolean(optionsOrCapture.passive);
-  } else {
-    capture = Boolean(optionsOrCapture);
-    once = false;
-    passive = false;
-  }
-  // Search the wrapped function.
-  let wrapperFn = undefined;
-  if (fn.__eventWrappers) {
-    for (let i = 0; i < fn.__eventWrappers.length; i++) {
-      if (fn.__eventWrappers[i].node === this &&
-          fn.__eventWrappers[i].type === type &&
-          fn.__eventWrappers[i].capture === capture &&
-          fn.__eventWrappers[i].once === once &&
-          fn.__eventWrappers[i].passive === passive) {
-        wrapperFn = fn.__eventWrappers.splice(i, 1)[0].wrapperFn;
-        // Cleanup.
-        if (!fn.__eventWrappers.length) {
-          fn.__eventWrappers = undefined;
-        }
-        break;
-      }
-    }
-  }
-
-  removeEventListener.call(this, type, wrapperFn || fn, optionsOrCapture);
-  if (wrapperFn && nonBubblingEventsToRetarget[type] &&
-      this.__handlers && this.__handlers[type]) {
-    const arr = this.__handlers[type][capture ? 'capture' : 'bubble'];
-    const idx = arr.indexOf(wrapperFn);
-    if (idx > -1) {
-      arr.splice(idx, 1);
-    }
-  }
-}
-
-function activateFocusEventOverrides() {
-  for (let ev in nonBubblingEventsToRetarget) {
-    window.addEventListener(ev, function(e) {
-      if (!e['__target']) {
-        patchEvent(e);
-        retargetNonBubblingEvent(e);
-        e.stopImmediatePropagation();
-      }
-    }, true);
-  }
-}
-
-function patchEvent(event) {
-  event['__target'] = event.target;
-  event.__relatedTarget = event.relatedTarget;
-  // patch event prototype if we can
-  if (settings.hasDescriptors) {
-    patchPrototype(event, eventMixin);
-  // and fallback to patching instance
-  } else {
-    extend(event, eventMixin);
-  }
-}
-
-let PatchedEvent = mixinComposedFlag(window.Event);
-let PatchedCustomEvent = mixinComposedFlag(window.CustomEvent);
-let PatchedMouseEvent = mixinComposedFlag(window.MouseEvent);
-
-function patchEvents() {
-  window.Event = PatchedEvent;
-  window.CustomEvent = PatchedCustomEvent;
-  window.MouseEvent = PatchedMouseEvent;
-  activateFocusEventOverrides();
-}
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-function newSplice(index, removed, addedCount) {
-  return {
-    index: index,
-    removed: removed,
-    addedCount: addedCount
-  };
-}
-
-const EDIT_LEAVE = 0;
-const EDIT_UPDATE = 1;
-const EDIT_ADD = 2;
-const EDIT_DELETE = 3;
-
-// Note: This function is *based* on the computation of the Levenshtein
-// "edit" distance. The one change is that "updates" are treated as two
-// edits - not one. With Array splices, an update is really a delete
-// followed by an add. By retaining this, we optimize for "keeping" the
-// maximum array items in the original array. For example:
-//
-//   'xxxx123' -> '123yyyy'
-//
-// With 1-edit updates, the shortest path would be just to update all seven
-// characters. With 2-edit updates, we delete 4, leave 3, and add 4. This
-// leaves the substring '123' intact.
-function calcEditDistances(current, currentStart, currentEnd,
-                            old, oldStart, oldEnd) {
-  // "Deletion" columns
-  let rowCount = oldEnd - oldStart + 1;
-  let columnCount = currentEnd - currentStart + 1;
-  let distances = new Array(rowCount);
-
-  // "Addition" rows. Initialize null column.
-  for (let i = 0; i < rowCount; i++) {
-    distances[i] = new Array(columnCount);
-    distances[i][0] = i;
-  }
-
-  // Initialize null row
-  for (let j = 0; j < columnCount; j++)
-    distances[0][j] = j;
-
-  for (let i = 1; i < rowCount; i++) {
-    for (let j = 1; j < columnCount; j++) {
-      if (equals(current[currentStart + j - 1], old[oldStart + i - 1]))
-        distances[i][j] = distances[i - 1][j - 1];
-      else {
-        let north = distances[i - 1][j] + 1;
-        let west = distances[i][j - 1] + 1;
-        distances[i][j] = north < west ? north : west;
-      }
-    }
-  }
-
-  return distances;
-}
-
-// This starts at the final weight, and walks "backward" by finding
-// the minimum previous weight recursively until the origin of the weight
-// matrix.
-function spliceOperationsFromEditDistances(distances) {
-  let i = distances.length - 1;
-  let j = distances[0].length - 1;
-  let current = distances[i][j];
-  let edits = [];
-  while (i > 0 || j > 0) {
-    if (i == 0) {
-      edits.push(EDIT_ADD);
-      j--;
-      continue;
-    }
-    if (j == 0) {
-      edits.push(EDIT_DELETE);
-      i--;
-      continue;
-    }
-    let northWest = distances[i - 1][j - 1];
-    let west = distances[i - 1][j];
-    let north = distances[i][j - 1];
-
-    let min;
-    if (west < north)
-      min = west < northWest ? west : northWest;
-    else
-      min = north < northWest ? north : northWest;
-
-    if (min == northWest) {
-      if (northWest == current) {
-        edits.push(EDIT_LEAVE);
-      } else {
-        edits.push(EDIT_UPDATE);
-        current = northWest;
-      }
-      i--;
-      j--;
-    } else if (min == west) {
-      edits.push(EDIT_DELETE);
-      i--;
-      current = west;
-    } else {
-      edits.push(EDIT_ADD);
-      j--;
-      current = north;
-    }
-  }
-
-  edits.reverse();
-  return edits;
-}
-
-/**
- * Splice Projection functions:
- *
- * A splice map is a representation of how a previous array of items
- * was transformed into a new array of items. Conceptually it is a list of
- * tuples of
- *
- *   <index, removed, addedCount>
- *
- * which are kept in ascending index order of. The tuple represents that at
- * the |index|, |removed| sequence of items were removed, and counting forward
- * from |index|, |addedCount| items were added.
- */
-
-/**
- * Lacking individual splice mutation information, the minimal set of
- * splices can be synthesized given the previous state and final state of an
- * array. The basic approach is to calculate the edit distance matrix and
- * choose the shortest path through it.
- *
- * Complexity: O(l * p)
- *   l: The length of the current array
- *   p: The length of the old array
- */
-function calcSplices(current, currentStart, currentEnd,
-                      old, oldStart, oldEnd) {
-  let prefixCount = 0;
-  let suffixCount = 0;
-  let splice;
-
-  let minLength = Math.min(currentEnd - currentStart, oldEnd - oldStart);
-  if (currentStart == 0 && oldStart == 0)
-    prefixCount = sharedPrefix(current, old, minLength);
-
-  if (currentEnd == current.length && oldEnd == old.length)
-    suffixCount = sharedSuffix(current, old, minLength - prefixCount);
-
-  currentStart += prefixCount;
-  oldStart += prefixCount;
-  currentEnd -= suffixCount;
-  oldEnd -= suffixCount;
-
-  if (currentEnd - currentStart == 0 && oldEnd - oldStart == 0)
-    return [];
-
-  if (currentStart == currentEnd) {
-    splice = newSplice(currentStart, [], 0);
-    while (oldStart < oldEnd)
-      splice.removed.push(old[oldStart++]);
-
-    return [ splice ];
-  } else if (oldStart == oldEnd)
-    return [ newSplice(currentStart, [], currentEnd - currentStart) ];
-
-  let ops = spliceOperationsFromEditDistances(
-      calcEditDistances(current, currentStart, currentEnd,
-                             old, oldStart, oldEnd));
-
-  splice = undefined;
-  let splices = [];
-  let index = currentStart;
-  let oldIndex = oldStart;
-  for (let i = 0; i < ops.length; i++) {
-    switch(ops[i]) {
-      case EDIT_LEAVE:
-        if (splice) {
-          splices.push(splice);
-          splice = undefined;
-        }
-
-        index++;
-        oldIndex++;
-        break;
-      case EDIT_UPDATE:
-        if (!splice)
-          splice = newSplice(index, [], 0);
-
-        splice.addedCount++;
-        index++;
-
-        splice.removed.push(old[oldIndex]);
-        oldIndex++;
-        break;
-      case EDIT_ADD:
-        if (!splice)
-          splice = newSplice(index, [], 0);
-
-        splice.addedCount++;
-        index++;
-        break;
-      case EDIT_DELETE:
-        if (!splice)
-          splice = newSplice(index, [], 0);
-
-        splice.removed.push(old[oldIndex]);
-        oldIndex++;
-        break;
-    }
-  }
-
-  if (splice) {
-    splices.push(splice);
-  }
-  return splices;
-}
-
-function sharedPrefix(current, old, searchLength) {
-  for (let i = 0; i < searchLength; i++)
-    if (!equals(current[i], old[i]))
-      return i;
-  return searchLength;
-}
-
-function sharedSuffix(current, old, searchLength) {
-  let index1 = current.length;
-  let index2 = old.length;
-  let count = 0;
-  while (count < searchLength && equals(current[--index1], old[--index2]))
-    count++;
-
-  return count;
-}
-
-function equals(currentValue, previousValue) {
-  return currentValue === previousValue;
-}
-
-function calculateSplices(current, previous) {
-  return calcSplices(current, 0, current.length, previous, 0,
-                          previous.length);
-}
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-// NOTE: normalize event contruction where necessary (IE11)
-let NormalizedEvent = typeof Event === 'function' ? Event :
-  function(inType, params) {
-    params = params || {};
-    var e = document.createEvent('Event');
-    e.initEvent(inType, Boolean(params.bubbles), Boolean(params.cancelable));
-    return e;
-  };
-
-var Distributor = class {
-
-  constructor(root) {
-    this.root = root;
-    this.insertionPointTag = 'slot';
-  }
-
-  getInsertionPoints() {
-    return this.root.querySelectorAll(this.insertionPointTag);
-  }
-
-  isInsertionPoint(node) {
-    return node.localName && node.localName == this.insertionPointTag;
-  }
-
-  distribute() {
-    if (this.root.hasInsertionPoint()) {
-      return this.distributePool(this.root, this.collectPool());
-    }
-    return [];
-  }
-
-  // Gather the pool of nodes that should be distributed. We will combine
-  // these with the "content root" to arrive at the composed tree.
-  collectPool() {
-    let host = this.root.host;
-    let pool=[], i=0;
-    for (let n=host.firstChild; n; n=n.nextSibling) {
-      pool[i++] = n;
-    }
-    return pool;
-  }
-
-  // perform "logical" distribution; note, no actual dom is moved here,
-  // instead elements are distributed into storage
-  // array where applicable.
-  distributePool(node, pool) {
-    let dirtyRoots = [];
-    let p$ = this.root._getInsertionPoints();
-    for (let i=0, l=p$.length, p; (i<l) && (p=p$[i]); i++) {
-      this.distributeInsertionPoint(p, pool);
-      // provoke redistribution on insertion point parents
-      // must do this on all candidate hosts since distribution in this
-      // scope invalidates their distribution.
-      // only get logical parent.
-      let parent = p.parentNode;
-      let root = parent && parent.__shady && parent.__shady.root;
-      if (root && root.hasInsertionPoint()) {
-        dirtyRoots.push(root);
-      }
-    }
-    for (let i=0; i < pool.length; i++) {
-      let p = pool[i];
-      if (p) {
-        p.__shady = p.__shady || {};
-        p.__shady.assignedSlot = undefined;
-        // remove undistributed elements from physical dom.
-        let parent = parentNode(p);
-        if (parent) {
-          removeChild.call(parent, p);
-        }
-      }
-    }
-    return dirtyRoots;
-  }
-
-  distributeInsertionPoint(insertionPoint, pool) {
-    let prevAssignedNodes = insertionPoint.__shady.assignedNodes;
-    if (prevAssignedNodes) {
-      this.clearAssignedSlots(insertionPoint, true);
-    }
-    insertionPoint.__shady.assignedNodes = [];
-    let needsSlotChange = false;
-    // distribute nodes from the pool that this selector matches
-    let anyDistributed = false;
-    for (let i=0, l=pool.length, node; i < l; i++) {
-      node=pool[i];
-      // skip nodes that were already used
-      if (!node) {
-        continue;
-      }
-      // distribute this node if it matches
-      if (this.matchesInsertionPoint(node, insertionPoint)) {
-        if (node.__shady._prevAssignedSlot != insertionPoint) {
-          needsSlotChange = true;
-        }
-        this.distributeNodeInto(node, insertionPoint);
-        // remove this node from the pool
-        pool[i] = undefined;
-        // since at least one node matched, we won't need fallback content
-        anyDistributed = true;
-      }
-    }
-    // Fallback content if nothing was distributed here
-    if (!anyDistributed) {
-      let children$$1 = insertionPoint.childNodes;
-      for (let j = 0, node; j < children$$1.length; j++) {
-        node = children$$1[j];
-        if (node.__shady._prevAssignedSlot != insertionPoint) {
-          needsSlotChange = true;
-        }
-        this.distributeNodeInto(node, insertionPoint);
-      }
-    }
-    // we're already dirty if a node was newly added to the slot
-    // and we're also dirty if the assigned count decreased.
-    if (prevAssignedNodes) {
-      // TODO(sorvell): the tracking of previously assigned slots
-      // could instead by done with a Set and then we could
-      // avoid needing to iterate here to clear the info.
-      for (let i=0; i < prevAssignedNodes.length; i++) {
-        prevAssignedNodes[i].__shady._prevAssignedSlot = null;
-      }
-      if (insertionPoint.__shady.assignedNodes.length < prevAssignedNodes.length) {
-        needsSlotChange = true;
-      }
-    }
-    this.setDistributedNodesOnInsertionPoint(insertionPoint);
-    if (needsSlotChange) {
-      this._fireSlotChange(insertionPoint);
-    }
-  }
-
-  clearAssignedSlots(slot, savePrevious) {
-    let n$ = slot.__shady.assignedNodes;
-    if (n$) {
-      for (let i=0; i < n$.length; i++) {
-        let n = n$[i];
-        if (savePrevious) {
-          n.__shady._prevAssignedSlot = n.__shady.assignedSlot;
-        }
-        // only clear if it was previously set to this slot;
-        // this helps ensure that if the node has otherwise been distributed
-        // ignore it.
-        if (n.__shady.assignedSlot === slot) {
-          n.__shady.assignedSlot = null;
-        }
-      }
-    }
-  }
-
-  matchesInsertionPoint(node, insertionPoint) {
-    let slotName = insertionPoint.getAttribute('name');
-    slotName = slotName ? slotName.trim() : '';
-    let slot = node.getAttribute && node.getAttribute('slot');
-    slot = slot ? slot.trim() : '';
-    return (slot == slotName);
-  }
-
-  distributeNodeInto(child, insertionPoint) {
-    insertionPoint.__shady.assignedNodes.push(child);
-    child.__shady.assignedSlot = insertionPoint;
-  }
-
-  setDistributedNodesOnInsertionPoint(insertionPoint) {
-    let n$ = insertionPoint.__shady.assignedNodes;
-    insertionPoint.__shady.distributedNodes = [];
-    for (let i=0, n; (i<n$.length) && (n=n$[i]) ; i++) {
-      if (this.isInsertionPoint(n)) {
-        let d$ = n.__shady.distributedNodes;
-        if (d$) {
-          for (let j=0; j < d$.length; j++) {
-            insertionPoint.__shady.distributedNodes.push(d$[j]);
-          }
-        }
-      } else {
-        insertionPoint.__shady.distributedNodes.push(n$[i]);
-      }
-    }
-  }
-
-  _fireSlotChange(insertionPoint) {
-    // NOTE: cannot bubble correctly here so not setting bubbles: true
-    // Safari tech preview does not bubble but chrome does
-    // Spec says it bubbles (https://dom.spec.whatwg.org/#mutation-observers)
-    insertionPoint.dispatchEvent(new NormalizedEvent('slotchange'));
-    if (insertionPoint.__shady.assignedSlot) {
-      this._fireSlotChange(insertionPoint.__shady.assignedSlot);
-    }
-  }
-
-  isFinalDestination(insertionPoint) {
-    return !(insertionPoint.__shady.assignedSlot);
-  }
-
-};
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-// Do not export this object. It must be passed as the first argument to the
-// ShadyRoot constructor in `attachShadow` to prevent the constructor from
-// throwing. This prevents the user from being able to manually construct a
-// ShadyRoot (i.e. `new ShadowRoot()`).
-const ShadyRootConstructionToken = {};
-
-/**
- * @constructor
- * @extends {ShadowRoot}
- */
-let ShadyRoot = function(token, host) {
-  if (token !== ShadyRootConstructionToken) {
-    throw new TypeError('Illegal constructor');
-  }
-  // NOTE: this strange construction is necessary because
-  // DocumentFragment cannot be subclassed on older browsers.
-  let shadowRoot = document.createDocumentFragment();
-  shadowRoot.__proto__ = ShadyRoot.prototype;
-  /** @type {ShadyRoot} */ (shadowRoot)._init(host);
-  return shadowRoot;
-};
-
-ShadyRoot.prototype = Object.create(DocumentFragment.prototype);
-
-ShadyRoot.prototype._init = function(host) {
-  // NOTE: set a fake local name so this element can be
-  // distinguished from a DocumentFragment when patching.
-  // FF doesn't allow this to be `localName`
-  this.__localName = 'ShadyRoot';
-  // logical dom setup
-  recordChildNodes(host);
-  recordChildNodes(this);
-  // root <=> host
-  host.shadowRoot = this;
-  this.host = host;
-  // state flags
-  this._renderPending = false;
-  this._hasRendered = false;
-  this._changePending = false;
-  this._distributor = new Distributor(this);
-  this.update();
-};
-
-
-// async render
-ShadyRoot.prototype.update = function() {
-  if (!this._renderPending) {
-    this._renderPending = true;
-    enqueue(() => this.render());
-  }
-};
-
-// returns the oldest renderPending ancestor root.
-ShadyRoot.prototype._getRenderRoot = function() {
-  let renderRoot = this;
-  let root = this;
-  while (root) {
-    if (root._renderPending) {
-      renderRoot = root;
-    }
-    root = root._rendererForHost();
-  }
-  return renderRoot;
-};
-
-// Returns the shadyRoot `this.host` if `this.host`
-// has children that require distribution.
-ShadyRoot.prototype._rendererForHost = function() {
-  let root = this.host.getRootNode();
-  if (isShadyRoot(root)) {
-    let c$ = this.host.childNodes;
-    for (let i=0, c; i < c$.length; i++) {
-      c = c$[i];
-      if (this._distributor.isInsertionPoint(c)) {
-        return root;
-      }
-    }
-  }
-};
-
-ShadyRoot.prototype.render = function() {
-  if (this._renderPending) {
-    this._getRenderRoot()['_render']();
-  }
-};
-
-// NOTE: avoid renaming to ease testability.
-ShadyRoot.prototype['_render'] = function() {
-  this._renderPending = false;
-  this._changePending = false;
-  if (!this._skipUpdateInsertionPoints) {
-    this.updateInsertionPoints();
-  } else if (!this._hasRendered) {
-    this.__insertionPoints = [];
-  }
-  this._skipUpdateInsertionPoints = false;
-  // TODO(sorvell): can add a first render optimization here
-  // to use if there are no insertion points
-  // 1. clear host node of composed children
-  // 2. appendChild the shadowRoot itself or (more robust) its logical children
-  // NOTE: this didn't seem worth it in perf testing
-  // but not ready to delete this info.
-  // logical
-  this.distribute();
-  // physical
-  this.compose();
-  this._hasRendered = true;
-};
-
-ShadyRoot.prototype.forceRender = function() {
-  this._renderPending = true;
-  this.render();
-};
-
-ShadyRoot.prototype.distribute = function() {
-  let dirtyRoots = this._distributor.distribute();
-  for (let i=0; i<dirtyRoots.length; i++) {
-    dirtyRoots[i]['_render']();
-  }
-};
-
-ShadyRoot.prototype.updateInsertionPoints = function() {
-  let i$ = this._insertionPoints;
-  // if any insertion points have been removed, clear their distribution info
-  if (i$) {
-    for (let i=0, c; i < i$.length; i++) {
-      c = i$[i];
-      if (c.getRootNode() !== this) {
-        this._distributor.clearAssignedSlots(c);
-      }
-    }
-  }
-  i$ = this._insertionPoints = this._distributor.getInsertionPoints();
-  // ensure insertionPoints's and their parents have logical dom info.
-  // save logical tree info
-  // a. for shadyRoot
-  // b. for insertion points (fallback)
-  // c. for parents of insertion points
-  for (let i=0, c; i < i$.length; i++) {
-    c = i$[i];
-    c.__shady = c.__shady || {};
-    recordChildNodes(c);
-    recordChildNodes(c.parentNode);
-  }
-};
-
-ShadyRoot.prototype.compose = function() {
-  // compose self
-  // note: it's important to mark this clean before distribution
-  // so that attachment that provokes additional distribution (e.g.
-  // adding something to your parentNode) works
-  this._composeTree();
-  // TODO(sorvell): See fast paths here in Polymer v1
-  // (these seem unnecessary)
-};
-
-// Reify dom such that it is at its correct rendering position
-// based on logical distribution.
-ShadyRoot.prototype._composeTree = function() {
-  this._updateChildNodes(this.host, this._composeNode(this.host));
-  let p$ = this._getInsertionPoints();
-  for (let i=0, l=p$.length, p, parent; (i<l) && (p=p$[i]); i++) {
-    parent = p.parentNode;
-    if ((parent !== this.host) && (parent !== this)) {
-      this._updateChildNodes(parent, this._composeNode(parent));
-    }
-  }
-};
-
-// Returns the list of nodes which should be rendered inside `node`.
-ShadyRoot.prototype._composeNode = function(node) {
-  let children$$1 = [];
-  let c$ = ((node.__shady && node.__shady.root) || node).childNodes;
-  for (let i = 0; i < c$.length; i++) {
-    let child = c$[i];
-    if (this._distributor.isInsertionPoint(child)) {
-      let distributedNodes = child.__shady.distributedNodes ||
-        (child.__shady.distributedNodes = []);
-      for (let j = 0; j < distributedNodes.length; j++) {
-        let distributedNode = distributedNodes[j];
-        if (this.isFinalDestination(child, distributedNode)) {
-          children$$1.push(distributedNode);
-        }
-      }
-    } else {
-      children$$1.push(child);
-    }
-  }
-  return children$$1;
-};
-
-ShadyRoot.prototype.isFinalDestination = function(insertionPoint, node) {
-  return this._distributor.isFinalDestination(
-    insertionPoint, node);
-};
-
-// Ensures that the rendered node list inside `container` is `children`.
-ShadyRoot.prototype._updateChildNodes = function(container, children$$1) {
-  let composed = childNodes(container);
-  let splices = calculateSplices(children$$1, composed);
-  // process removals
-  for (let i=0, d=0, s; (i<splices.length) && (s=splices[i]); i++) {
-    for (let j=0, n; (j < s.removed.length) && (n=s.removed[j]); j++) {
-      // check if the node is still where we expect it is before trying
-      // to remove it; this can happen if we move a node and
-      // then schedule its previous host for distribution resulting in
-      // the node being removed here.
-      if (parentNode(n) === container) {
-        removeChild.call(container, n);
-      }
-      composed.splice(s.index + d, 1);
-    }
-    d -= s.addedCount;
-  }
-  // process adds
-  for (let i=0, s, next; (i<splices.length) && (s=splices[i]); i++) { //eslint-disable-line no-redeclare
-    next = composed[s.index];
-    for (let j=s.index, n; j < s.index + s.addedCount; j++) {
-      n = children$$1[j];
-      insertBefore.call(container, n, next);
-      // TODO(sorvell): is this splice strictly needed?
-      composed.splice(j, 0, n);
-    }
-  }
-};
-
-ShadyRoot.prototype.getInsertionPointTag = function() {
-  return this._distributor.insertionPointTag;
-};
-
-ShadyRoot.prototype.hasInsertionPoint = function() {
-  return Boolean(this._insertionPoints && this._insertionPoints.length);
-};
-
-ShadyRoot.prototype._getInsertionPoints = function() {
-  if (!this._insertionPoints) {
-    this.updateInsertionPoints();
-  }
-  return this._insertionPoints;
-};
-
-/**
-  Implements a pared down version of ShadowDOM's scoping, which is easy to
-  polyfill across browsers.
-*/
-function attachShadow(host, options) {
-  if (!host) {
-    throw 'Must provide a host.';
-  }
-  if (!options) {
-    throw 'Not enough arguments.'
-  }
-  return new ShadyRoot(ShadyRootConstructionToken, host);
-}
-
-patchShadowRootAccessors(ShadyRoot.prototype);
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-function getAssignedSlot(node) {
-  renderRootNode(node);
-  return node.__shady && node.__shady.assignedSlot || null;
-}
-
-let nodeMixin = {
-
-  addEventListener: addEventListener$1,
-
-  removeEventListener: removeEventListener$1,
-
-  appendChild(node) {
-    return insertBefore$1(this, node);
-  },
-
-  insertBefore(node, ref_node) {
-    return insertBefore$1(this, node, ref_node);
-  },
-
-  removeChild(node) {
-    return removeChild$1(this, node);
-  },
-
-  /**
-   * @this {Node}
-   */
-  replaceChild(node, ref_node) {
-    this.insertBefore(node, ref_node);
-    this.removeChild(ref_node);
-    return node;
-  },
-
-  /**
-   * @this {Node}
-   */
-  cloneNode(deep) {
-    return cloneNode$1(this, deep);
-  },
-
-  /**
-   * @this {Node}
-   */
-  getRootNode(options) {
-    return getRootNode(this, options);
-  },
-
-  /**
-   * @this {Node}
-   */
-  get isConnected() {
-    // Fast path for distributed nodes.
-    const ownerDocument = this.ownerDocument;
-    if (ownerDocument && ownerDocument.contains && ownerDocument.contains(this)) return true;
-    const ownerDocumentElement = ownerDocument.documentElement;
-    if (ownerDocumentElement && ownerDocumentElement.contains && ownerDocumentElement.contains(this)) return true;
-
-    let node = this;
-    while (node && !(node instanceof Document)) {
-      node = node.parentNode || (node instanceof ShadyRoot ? /** @type {ShadowRoot} */(node).host : undefined);
-    }
-    return !!(node && node instanceof Document);
-  }
-
-};
-
-// NOTE: For some reason `Text` redefines `assignedSlot`
-let textMixin = {
-  /**
-   * @this {Text}
-   */
-  get assignedSlot() {
-    return getAssignedSlot(this);
-  }
-};
-
-let fragmentMixin = {
-
-  // TODO(sorvell): consider doing native QSA and filtering results.
-  /**
-   * @this {DocumentFragment}
-   */
-  querySelector(selector) {
-    // match selector and halt on first result.
-    let result = query(this, function(n) {
-      return matchesSelector(n, selector);
-    }, function(n) {
-      return Boolean(n);
-    })[0];
-    return result || null;
-  },
-
-  /**
-   * @this {DocumentFragment}
-   */
-  querySelectorAll(selector) {
-    return query(this, function(n) {
-      return matchesSelector(n, selector);
-    });
-  }
-
-};
-
-let slotMixin = {
-
-  /**
-   * @this {HTMLSlotElement}
-   */
-  assignedNodes(options) {
-    if (this.localName === 'slot') {
-      renderRootNode(this);
-      return this.__shady ?
-        ((options && options.flatten ? this.__shady.distributedNodes :
-        this.__shady.assignedNodes) || []) :
-        [];
-    }
-  }
-
-};
-
-let elementMixin = extendAll({
-
-  /**
-   * @this {HTMLElement}
-   */
-  setAttribute(name, value) {
-    setAttribute$1(this, name, value);
-  },
-
-  /**
-   * @this {HTMLElement}
-   */
-  removeAttribute(name) {
-    removeAttribute$1(this, name);
-  },
-
-  /**
-   * @this {HTMLElement}
-   */
-  attachShadow(options) {
-    return attachShadow(this, options);
-  },
-
-  /**
-   * @this {HTMLElement}
-   */
-  get slot() {
-    return this.getAttribute('slot');
-  },
-
-  /**
-   * @this {HTMLElement}
-   */
-  set slot(value) {
-    this.setAttribute('slot', value);
-  },
-
-  /**
-   * @this {HTMLElement}
-   */
-  get assignedSlot() {
-    return getAssignedSlot(this);
-  }
-
-}, fragmentMixin, slotMixin);
-
-Object.defineProperties(elementMixin, ShadowRootAccessor);
-
-let documentMixin = extendAll({
-  /**
-   * @this {Document}
-   */
-  importNode(node, deep) {
-    return importNode$1(node, deep);
-  }
-}, fragmentMixin);
-
-Object.defineProperties(documentMixin, {
-  '_activeElement': ActiveElementAccessor.activeElement
-});
-
-function patchBuiltin(proto, obj) {
-  let n$ = Object.getOwnPropertyNames(obj);
-  for (let i=0; i < n$.length; i++) {
-    let n = n$[i];
-    let d = Object.getOwnPropertyDescriptor(obj, n);
-    // NOTE: we prefer writing directly here because some browsers
-    // have descriptors that are writable but not configurable (e.g.
-    // `appendChild` on older browsers)
-    if (d.value) {
-      proto[n] = d.value;
-    } else {
-      Object.defineProperty(proto, n, d);
-    }
-  }
-}
-
-
-// Apply patches to builtins (e.g. Element.prototype). Some of these patches
-// can be done unconditionally (mostly methods like
-// `Element.prototype.appendChild`) and some can only be done when the browser
-// has proper descriptors on the builtin prototype
-// (e.g. `Element.prototype.firstChild`)`. When descriptors are not available,
-// elements are individually patched when needed (see e.g.
-// `patchInside/OutsideElementAccessors` in `patch-accessors.js`).
-function patchBuiltins() {
-  // These patches can always be done, for all supported browsers.
-  patchBuiltin(window.Node.prototype, nodeMixin);
-  patchBuiltin(window.Text.prototype, textMixin);
-  patchBuiltin(window.DocumentFragment.prototype, fragmentMixin);
-  patchBuiltin(window.Element.prototype, elementMixin);
-  patchBuiltin(window.Document.prototype, documentMixin);
-  if (window.HTMLSlotElement) {
-    patchBuiltin(window.HTMLSlotElement.prototype, slotMixin);
-  }
-  // These patches can *only* be done
-  // on browsers that have proper property descriptors on builtin prototypes.
-  // This includes: IE11, Edge, Chrome >= 4?; Safari >= 10, Firefox
-  // On older browsers (Chrome <= 4?, Safari 9), a per element patching
-  // strategy is used for patching accessors.
-  if (settings.hasDescriptors) {
-    patchAccessors(window.Node.prototype);
-    patchAccessors(window.Text.prototype);
-    patchAccessors(window.DocumentFragment.prototype);
-    patchAccessors(window.Element.prototype);
-    let nativeHTMLElement =
-      (window['customElements'] && window['customElements']['nativeHTMLElement']) ||
-      HTMLElement;
-    patchAccessors(nativeHTMLElement.prototype);
-    patchAccessors(window.Document.prototype);
-    if (window.HTMLSlotElement) {
-      patchAccessors(window.HTMLSlotElement.prototype);
-    }
-  }
-}
-
-/**
-@license
-Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/**
- * Patches elements that interacts with ShadyDOM
- * such that tree traversal and mutation apis act like they would under
- * ShadowDOM.
- *
- * This import enables seemless interaction with ShadyDOM powered
- * custom elements, enabling better interoperation with 3rd party code,
- * libraries, and frameworks that use DOM tree manipulation apis.
- */
-
-if (settings.inUse) {
-  let ShadyDOM = {
-    // TODO(sorvell): remove when Polymer does not depend on this.
-    'inUse': settings.inUse,
-    // TODO(sorvell): remove when Polymer does not depend on this
-    'patch': (node) => node,
-    'isShadyRoot': isShadyRoot,
-    'enqueue': enqueue,
-    'flush': flush,
-    'settings': settings,
-    'filterMutations': filterMutations,
-    'observeChildren': observeChildren,
-    'unobserveChildren': unobserveChildren,
-    'nativeMethods': nativeMethods,
-    'nativeTree': nativeTree
-  };
-
-  window['ShadyDOM'] = ShadyDOM;
-
-  // Apply patches to events...
-  patchEvents();
-  // Apply patches to builtins (e.g. Element.prototype) where applicable.
-  patchBuiltins();
-
-  window.ShadowRoot = ShadyRoot;
-}
-
-const reservedTagList = new Set([
-  'annotation-xml',
-  'color-profile',
-  'font-face',
-  'font-face-src',
-  'font-face-uri',
-  'font-face-format',
-  'font-face-name',
-  'missing-glyph',
-]);
-
-/**
- * @param {string} localName
- * @returns {boolean}
- */
-function isValidCustomElementName(localName) {
-  const reserved = reservedTagList.has(localName);
-  const validForm = /^[a-z][.0-9_a-z]*-[\-.0-9_a-z]*$/.test(localName);
-  return !reserved && validForm;
-}
-
-/**
- * @private
- * @param {!Node} node
- * @return {boolean}
- */
-function isConnected(node) {
-  // Use `Node#isConnected`, if defined.
-  const nativeValue = node.isConnected;
-  if (nativeValue !== undefined) {
-    return nativeValue;
-  }
-
-  /** @type {?Node|undefined} */
-  let current = node;
-  while (current && !(current.__CE_isImportDocument || current instanceof Document)) {
-    current = current.parentNode || (window.ShadowRoot && current instanceof ShadowRoot ? current.host : undefined);
-  }
-  return !!(current && (current.__CE_isImportDocument || current instanceof Document));
-}
-
-/**
- * @param {!Node} root
- * @param {!Node} start
- * @return {?Node}
- */
-function nextSiblingOrAncestorSibling(root, start) {
-  let node = start;
-  while (node && node !== root && !node.nextSibling) {
-    node = node.parentNode;
-  }
-  return (!node || node === root) ? null : node.nextSibling;
-}
-
-/**
- * @param {!Node} root
- * @param {!Node} start
- * @return {?Node}
- */
-function nextNode(root, start) {
-  return start.firstChild ? start.firstChild : nextSiblingOrAncestorSibling(root, start);
-}
-
-/**
- * @param {!Node} root
- * @param {!function(!Element)} callback
- * @param {!Set<Node>=} visitedImports
- */
-function walkDeepDescendantElements(root, callback, visitedImports = new Set()) {
-  let node = root;
-  while (node) {
-    if (node.nodeType === Node.ELEMENT_NODE) {
-      const element = /** @type {!Element} */(node);
-
-      callback(element);
-
-      const localName = element.localName;
-      if (localName === 'link' && element.getAttribute('rel') === 'import') {
-        // If this import (polyfilled or not) has it's root node available,
-        // walk it.
-        const importNode = /** @type {!Node} */ (element.import);
-        if (importNode instanceof Node && !visitedImports.has(importNode)) {
-          // Prevent multiple walks of the same import root.
-          visitedImports.add(importNode);
-
-          for (let child = importNode.firstChild; child; child = child.nextSibling) {
-            walkDeepDescendantElements(child, callback, visitedImports);
-          }
-        }
-
-        // Ignore descendants of import links to prevent attempting to walk the
-        // elements created by the HTML Imports polyfill that we just walked
-        // above.
-        node = nextSiblingOrAncestorSibling(root, element);
-        continue;
-      } else if (localName === 'template') {
-        // Ignore descendants of templates. There shouldn't be any descendants
-        // because they will be moved into `.content` during construction in
-        // browsers that support template but, in case they exist and are still
-        // waiting to be moved by a polyfill, they will be ignored.
-        node = nextSiblingOrAncestorSibling(root, element);
-        continue;
-      }
-
-      // Walk shadow roots.
-      const shadowRoot = element.__CE_shadowRoot;
-      if (shadowRoot) {
-        for (let child = shadowRoot.firstChild; child; child = child.nextSibling) {
-          walkDeepDescendantElements(child, callback, visitedImports);
-        }
-      }
-    }
-
-    node = nextNode(root, node);
-  }
-}
-
-/**
- * Used to suppress Closure's "Modifying the prototype is only allowed if the
- * constructor is in the same scope" warning without using
- * `@suppress {newCheckTypes, duplicate}` because `newCheckTypes` is too broad.
- *
- * @param {!Object} destination
- * @param {string} name
- * @param {*} value
- */
-function setPropertyUnchecked(destination, name, value) {
-  destination[name] = value;
-}
-
-/**
- * @enum {number}
- */
-const CustomElementState = {
-  custom: 1,
-  failed: 2,
-};
-
-class CustomElementInternals {
-  constructor() {
-    /** @type {!Map<string, !CustomElementDefinition>} */
-    this._localNameToDefinition = new Map();
-
-    /** @type {!Map<!Function, !CustomElementDefinition>} */
-    this._constructorToDefinition = new Map();
-
-    /** @type {!Array<!function(!Node)>} */
-    this._patches = [];
-
-    /** @type {boolean} */
-    this._hasPatches = false;
-  }
-
-  /**
-   * @param {string} localName
-   * @param {!CustomElementDefinition} definition
-   */
-  setDefinition(localName, definition) {
-    this._localNameToDefinition.set(localName, definition);
-    this._constructorToDefinition.set(definition.constructor, definition);
-  }
-
-  /**
-   * @param {string} localName
-   * @return {!CustomElementDefinition|undefined}
-   */
-  localNameToDefinition(localName) {
-    return this._localNameToDefinition.get(localName);
-  }
-
-  /**
-   * @param {!Function} constructor
-   * @return {!CustomElementDefinition|undefined}
-   */
-  constructorToDefinition(constructor) {
-    return this._constructorToDefinition.get(constructor);
-  }
-
-  /**
-   * @param {!function(!Node)} listener
-   */
-  addPatch(listener) {
-    this._hasPatches = true;
-    this._patches.push(listener);
-  }
-
-  /**
-   * @param {!Node} node
-   */
-  patchTree(node) {
-    if (!this._hasPatches) return;
-
-    walkDeepDescendantElements(node, element => this.patch(element));
-  }
-
-  /**
-   * @param {!Node} node
-   */
-  patch(node) {
-    if (!this._hasPatches) return;
-
-    if (node.__CE_patched) return;
-    node.__CE_patched = true;
-
-    for (let i = 0; i < this._patches.length; i++) {
-      this._patches[i](node);
-    }
-  }
-
-  /**
-   * @param {!Node} root
-   */
-  connectTree(root) {
-    const elements = [];
-
-    walkDeepDescendantElements(root, element => elements.push(element));
-
-    for (let i = 0; i < elements.length; i++) {
-      const element = elements[i];
-      if (element.__CE_state === CustomElementState.custom) {
-        this.connectedCallback(element);
-      } else {
-        this.upgradeElement(element);
-      }
-    }
-  }
-
-  /**
-   * @param {!Node} root
-   */
-  disconnectTree(root) {
-    const elements = [];
-
-    walkDeepDescendantElements(root, element => elements.push(element));
-
-    for (let i = 0; i < elements.length; i++) {
-      const element = elements[i];
-      if (element.__CE_state === CustomElementState.custom) {
-        this.disconnectedCallback(element);
-      }
-    }
-  }
-
-  /**
-   * Upgrades all uncustomized custom elements at and below a root node for
-   * which there is a definition. When custom element reaction callbacks are
-   * assumed to be called synchronously (which, by the current DOM / HTML spec
-   * definitions, they are *not*), callbacks for both elements customized
-   * synchronously by the parser and elements being upgraded occur in the same
-   * relative order.
-   *
-   * NOTE: This function, when used to simulate the construction of a tree that
-   * is already created but not customized (i.e. by the parser), does *not*
-   * prevent the element from reading the 'final' (true) state of the tree. For
-   * example, the element, during truly synchronous parsing / construction would
-   * see that it contains no children as they have not yet been inserted.
-   * However, this function does not modify the tree, the element will
-   * (incorrectly) have children. Additionally, self-modification restrictions
-   * for custom element constructors imposed by the DOM spec are *not* enforced.
-   *
-   *
-   * The following nested list shows the steps extending down from the HTML
-   * spec's parsing section that cause elements to be synchronously created and
-   * upgraded:
-   *
-   * The "in body" insertion mode:
-   * https://html.spec.whatwg.org/multipage/syntax.html#parsing-main-inbody
-   * - Switch on token:
-   *   .. other cases ..
-   *   -> Any other start tag
-   *      - [Insert an HTML element](below) for the token.
-   *
-   * Insert an HTML element:
-   * https://html.spec.whatwg.org/multipage/syntax.html#insert-an-html-element
-   * - Insert a foreign element for the token in the HTML namespace:
-   *   https://html.spec.whatwg.org/multipage/syntax.html#insert-a-foreign-element
-   *   - Create an element for a token:
-   *     https://html.spec.whatwg.org/multipage/syntax.html#create-an-element-for-the-token
-   *     - Will execute script flag is true?
-   *       - (Element queue pushed to the custom element reactions stack.)
-   *     - Create an element:
-   *       https://dom.spec.whatwg.org/#concept-create-element
-   *       - Sync CE flag is true?
-   *         - Constructor called.
-   *         - Self-modification restrictions enforced.
-   *       - Sync CE flag is false?
-   *         - (Upgrade reaction enqueued.)
-   *     - Attributes appended to element.
-   *       (`attributeChangedCallback` reactions enqueued.)
-   *     - Will execute script flag is true?
-   *       - (Element queue popped from the custom element reactions stack.
-   *         Reactions in the popped stack are invoked.)
-   *   - (Element queue pushed to the custom element reactions stack.)
-   *   - Insert the element:
-   *     https://dom.spec.whatwg.org/#concept-node-insert
-   *     - Shadow-including descendants are connected. During parsing
-   *       construction, there are no shadow-*excluding* descendants.
-   *       However, the constructor may have validly attached a shadow
-   *       tree to itself and added descendants to that shadow tree.
-   *       (`connectedCallback` reactions enqueued.)
-   *   - (Element queue popped from the custom element reactions stack.
-   *     Reactions in the popped stack are invoked.)
-   *
-   * @param {!Node} root
-   * @param {!Set<Node>=} visitedImports
-   */
-  patchAndUpgradeTree(root, visitedImports = new Set()) {
-    const elements = [];
-
-    const gatherElements = element => {
-      if (element.localName === 'link' && element.getAttribute('rel') === 'import') {
-        // The HTML Imports polyfill sets a descendant element of the link to
-        // the `import` property, specifically this is *not* a Document.
-        const importNode = /** @type {?Node} */ (element.import);
-
-        if (importNode instanceof Node && importNode.readyState === 'complete') {
-          importNode.__CE_isImportDocument = true;
-
-          // Connected links are associated with the registry.
-          importNode.__CE_hasRegistry = true;
-        } else {
-          // If this link's import root is not available, its contents can't be
-          // walked. Wait for 'load' and walk it when it's ready.
-          element.addEventListener('load', () => {
-            const importNode = /** @type {!Node} */ (element.import);
-
-            if (importNode.__CE_documentLoadHandled) return;
-            importNode.__CE_documentLoadHandled = true;
-
-            importNode.__CE_isImportDocument = true;
-
-            // Connected links are associated with the registry.
-            importNode.__CE_hasRegistry = true;
-
-            // Clone the `visitedImports` set that was populated sync during
-            // the `patchAndUpgradeTree` call that caused this 'load' handler to
-            // be added. Then, remove *this* link's import node so that we can
-            // walk that import again, even if it was partially walked later
-            // during the same `patchAndUpgradeTree` call.
-            const clonedVisitedImports = new Set(visitedImports);
-            visitedImports.delete(importNode);
-
-            this.patchAndUpgradeTree(importNode, visitedImports);
-          });
-        }
-      } else {
-        elements.push(element);
-      }
-    };
-
-    // `walkDeepDescendantElements` populates (and internally checks against)
-    // `visitedImports` when traversing a loaded import.
-    walkDeepDescendantElements(root, gatherElements, visitedImports);
-
-    if (this._hasPatches) {
-      for (let i = 0; i < elements.length; i++) {
-        this.patch(elements[i]);
-      }
-    }
-
-    for (let i = 0; i < elements.length; i++) {
-      this.upgradeElement(elements[i]);
-    }
-  }
-
-  /**
-   * @param {!Element} element
-   */
-  upgradeElement(element) {
-    const currentState = element.__CE_state;
-    if (currentState !== undefined) return;
-
-    const definition = this.localNameToDefinition(element.localName);
-    if (!definition) return;
-
-    definition.constructionStack.push(element);
-
-    const constructor = definition.constructor;
-    try {
-      try {
-        let result = new (constructor)();
-        if (result !== element) {
-          throw new Error('The custom element constructor did not produce the element being upgraded.');
-        }
-      } finally {
-        definition.constructionStack.pop();
-      }
-    } catch (e) {
-      element.__CE_state = CustomElementState.failed;
-      throw e;
-    }
-
-    element.__CE_state = CustomElementState.custom;
-    element.__CE_definition = definition;
-
-    if (definition.attributeChangedCallback) {
-      const observedAttributes = definition.observedAttributes;
-      for (let i = 0; i < observedAttributes.length; i++) {
-        const name = observedAttributes[i];
-        const value = element.getAttribute(name);
-        if (value !== null) {
-          this.attributeChangedCallback(element, name, null, value, null);
-        }
-      }
-    }
-
-    if (isConnected(element)) {
-      this.connectedCallback(element);
-    }
-  }
-
-  /**
-   * @param {!Element} element
-   */
-  connectedCallback(element) {
-    const definition = element.__CE_definition;
-    if (definition.connectedCallback) {
-      definition.connectedCallback.call(element);
-    }
-  }
-
-  /**
-   * @param {!Element} element
-   */
-  disconnectedCallback(element) {
-    const definition = element.__CE_definition;
-    if (definition.disconnectedCallback) {
-      definition.disconnectedCallback.call(element);
-    }
-  }
-
-  /**
-   * @param {!Element} element
-   * @param {string} name
-   * @param {?string} oldValue
-   * @param {?string} newValue
-   * @param {?string} namespace
-   */
-  attributeChangedCallback(element, name, oldValue, newValue, namespace) {
-    const definition = element.__CE_definition;
-    if (
-      definition.attributeChangedCallback &&
-      definition.observedAttributes.indexOf(name) > -1
-    ) {
-      definition.attributeChangedCallback.call(element, name, oldValue, newValue, namespace);
-    }
-  }
-}
-
-class DocumentConstructionObserver {
-  constructor(internals, doc) {
-    /**
-     * @type {!CustomElementInternals}
-     */
-    this._internals = internals;
-
-    /**
-     * @type {!Document}
-     */
-    this._document = doc;
-
-    /**
-     * @type {MutationObserver|undefined}
-     */
-    this._observer = undefined;
-
-
-    // Simulate tree construction for all currently accessible nodes in the
-    // document.
-    this._internals.patchAndUpgradeTree(this._document);
-
-    if (this._document.readyState === 'loading') {
-      this._observer = new MutationObserver(this._handleMutations.bind(this));
-
-      // Nodes created by the parser are given to the observer *before* the next
-      // task runs. Inline scripts are run in a new task. This means that the
-      // observer will be able to handle the newly parsed nodes before the inline
-      // script is run.
-      this._observer.observe(this._document, {
-        childList: true,
-        subtree: true,
-      });
-    }
-  }
-
-  disconnect() {
-    if (this._observer) {
-      this._observer.disconnect();
-    }
-  }
-
-  /**
-   * @param {!Array<!MutationRecord>} mutations
-   */
-  _handleMutations(mutations) {
-    // Once the document's `readyState` is 'interactive' or 'complete', all new
-    // nodes created within that document will be the result of script and
-    // should be handled by patching.
-    const readyState = this._document.readyState;
-    if (readyState === 'interactive' || readyState === 'complete') {
-      this.disconnect();
-    }
-
-    for (let i = 0; i < mutations.length; i++) {
-      const addedNodes = mutations[i].addedNodes;
-      for (let j = 0; j < addedNodes.length; j++) {
-        const node = addedNodes[j];
-        this._internals.patchAndUpgradeTree(node);
-      }
-    }
-  }
-}
-
-/**
- * @template T
- */
-class Deferred {
-  constructor() {
-    /**
-     * @private
-     * @type {T|undefined}
-     */
-    this._value = undefined;
-
-    /**
-     * @private
-     * @type {Function|undefined}
-     */
-    this._resolve = undefined;
-
-    /**
-     * @private
-     * @type {!Promise<T>}
-     */
-    this._promise = new Promise(resolve => {
-      this._resolve = resolve;
-
-      if (this._value) {
-        resolve(this._value);
-      }
-    });
-  }
-
-  /**
-   * @param {T} value
-   */
-  resolve(value) {
-    if (this._value) {
-      throw new Error('Already resolved.');
-    }
-
-    this._value = value;
-
-    if (this._resolve) {
-      this._resolve(value);
-    }
-  }
-
-  /**
-   * @return {!Promise<T>}
-   */
-  toPromise() {
-    return this._promise;
-  }
-}
-
-/**
- * @unrestricted
- */
-class CustomElementRegistry {
-
-  /**
-   * @param {!CustomElementInternals} internals
-   */
-  constructor(internals) {
-    /**
-     * @private
-     * @type {boolean}
-     */
-    this._elementDefinitionIsRunning = false;
-
-    /**
-     * @private
-     * @type {!CustomElementInternals}
-     */
-    this._internals = internals;
-
-    /**
-     * @private
-     * @type {!Map<string, !Deferred<undefined>>}
-     */
-    this._whenDefinedDeferred = new Map();
-
-    /**
-     * The default flush callback triggers the document walk synchronously.
-     * @private
-     * @type {!Function}
-     */
-    this._flushCallback = fn => fn();
-
-    /**
-     * @private
-     * @type {boolean}
-     */
-    this._flushPending = false;
-
-    /**
-     * @private
-     * @type {!Array<string>}
-     */
-    this._unflushedLocalNames = [];
-
-    /**
-     * @private
-     * @type {!DocumentConstructionObserver}
-     */
-    this._documentConstructionObserver = new DocumentConstructionObserver(internals, document);
-  }
-
-  /**
-   * @param {string} localName
-   * @param {!Function} constructor
-   */
-  define(localName, constructor) {
-    if (!(constructor instanceof Function)) {
-      throw new TypeError('Custom element constructors must be functions.');
-    }
-
-    if (!isValidCustomElementName(localName)) {
-      throw new SyntaxError(`The element name '${localName}' is not valid.`);
-    }
-
-    if (this._internals.localNameToDefinition(localName)) {
-      throw new Error(`A custom element with name '${localName}' has already been defined.`);
-    }
-
-    if (this._elementDefinitionIsRunning) {
-      throw new Error('A custom element is already being defined.');
-    }
-    this._elementDefinitionIsRunning = true;
-
-    let connectedCallback;
-    let disconnectedCallback;
-    let adoptedCallback;
-    let attributeChangedCallback;
-    let observedAttributes;
-    try {
-      /** @type {!Object} */
-      const prototype = constructor.prototype;
-      if (!(prototype instanceof Object)) {
-        throw new TypeError('The custom element constructor\'s prototype is not an object.');
-      }
-
-      function getCallback(name) {
-        const callbackValue = prototype[name];
-        if (callbackValue !== undefined && !(callbackValue instanceof Function)) {
-          throw new Error(`The '${name}' callback must be a function.`);
-        }
-        return callbackValue;
-      }
-
-      connectedCallback = getCallback('connectedCallback');
-      disconnectedCallback = getCallback('disconnectedCallback');
-      adoptedCallback = getCallback('adoptedCallback');
-      attributeChangedCallback = getCallback('attributeChangedCallback');
-      observedAttributes = constructor['observedAttributes'] || [];
-    } catch (e) {
-      return;
-    } finally {
-      this._elementDefinitionIsRunning = false;
-    }
-
-    const definition = {
-      localName,
-      constructor,
-      connectedCallback,
-      disconnectedCallback,
-      adoptedCallback,
-      attributeChangedCallback,
-      observedAttributes,
-      constructionStack: [],
-    };
-
-    this._internals.setDefinition(localName, definition);
-
-    this._unflushedLocalNames.push(localName);
-
-    // If we've already called the flush callback and it hasn't called back yet,
-    // don't call it again.
-    if (!this._flushPending) {
-      this._flushPending = true;
-      this._flushCallback(() => this._flush());
-    }
-  }
-
-  _flush() {
-    // If no new definitions were defined, don't attempt to flush. This could
-    // happen if a flush callback keeps the function it is given and calls it
-    // multiple times.
-    if (this._flushPending === false) return;
-
-    this._flushPending = false;
-    this._internals.patchAndUpgradeTree(document);
-
-    while (this._unflushedLocalNames.length > 0) {
-      const localName = this._unflushedLocalNames.shift();
-      const deferred = this._whenDefinedDeferred.get(localName);
-      if (deferred) {
-        deferred.resolve(undefined);
-      }
-    }
-  }
-
-  /**
-   * @param {string} localName
-   * @return {Function|undefined}
-   */
-  get(localName) {
-    const definition = this._internals.localNameToDefinition(localName);
-    if (definition) {
-      return definition.constructor;
-    }
-
-    return undefined;
-  }
-
-  /**
-   * @param {string} localName
-   * @return {!Promise<undefined>}
-   */
-  whenDefined(localName) {
-    if (!isValidCustomElementName(localName)) {
-      return Promise.reject(new SyntaxError(`'${localName}' is not a valid custom element name.`));
-    }
-
-    const prior = this._whenDefinedDeferred.get(localName);
-    if (prior) {
-      return prior.toPromise();
-    }
-
-    const deferred = new Deferred();
-    this._whenDefinedDeferred.set(localName, deferred);
-
-    const definition = this._internals.localNameToDefinition(localName);
-    // Resolve immediately only if the given local name has a definition *and*
-    // the full document walk to upgrade elements with that local name has
-    // already happened.
-    if (definition && this._unflushedLocalNames.indexOf(localName) === -1) {
-      deferred.resolve(undefined);
-    }
-
-    return deferred.toPromise();
-  }
-
-  polyfillWrapFlushCallback(outer) {
-    this._documentConstructionObserver.disconnect();
-    const inner = this._flushCallback;
-    this._flushCallback = flush => outer(() => inner(flush));
-  }
-}
-
-// Closure compiler exports.
-window['CustomElementRegistry'] = CustomElementRegistry;
-CustomElementRegistry.prototype['define'] = CustomElementRegistry.prototype.define;
-CustomElementRegistry.prototype['get'] = CustomElementRegistry.prototype.get;
-CustomElementRegistry.prototype['whenDefined'] = CustomElementRegistry.prototype.whenDefined;
-CustomElementRegistry.prototype['polyfillWrapFlushCallback'] = CustomElementRegistry.prototype.polyfillWrapFlushCallback;
-
-var Native = {
-  Document_createElement: window.Document.prototype.createElement,
-  Document_createElementNS: window.Document.prototype.createElementNS,
-  Document_importNode: window.Document.prototype.importNode,
-  Document_prepend: window.Document.prototype['prepend'],
-  Document_append: window.Document.prototype['append'],
-  Node_cloneNode: window.Node.prototype.cloneNode,
-  Node_appendChild: window.Node.prototype.appendChild,
-  Node_insertBefore: window.Node.prototype.insertBefore,
-  Node_removeChild: window.Node.prototype.removeChild,
-  Node_replaceChild: window.Node.prototype.replaceChild,
-  Node_textContent: Object.getOwnPropertyDescriptor(window.Node.prototype, 'textContent'),
-  Element_attachShadow: window.Element.prototype['attachShadow'],
-  Element_innerHTML: Object.getOwnPropertyDescriptor(window.Element.prototype, 'innerHTML'),
-  Element_getAttribute: window.Element.prototype.getAttribute,
-  Element_setAttribute: window.Element.prototype.setAttribute,
-  Element_removeAttribute: window.Element.prototype.removeAttribute,
-  Element_getAttributeNS: window.Element.prototype.getAttributeNS,
-  Element_setAttributeNS: window.Element.prototype.setAttributeNS,
-  Element_removeAttributeNS: window.Element.prototype.removeAttributeNS,
-  Element_insertAdjacentElement: window.Element.prototype['insertAdjacentElement'],
-  Element_prepend: window.Element.prototype['prepend'],
-  Element_append: window.Element.prototype['append'],
-  Element_before: window.Element.prototype['before'],
-  Element_after: window.Element.prototype['after'],
-  Element_replaceWith: window.Element.prototype['replaceWith'],
-  Element_remove: window.Element.prototype['remove'],
-  HTMLElement: window.HTMLElement,
-  HTMLElement_innerHTML: Object.getOwnPropertyDescriptor(window.HTMLElement.prototype, 'innerHTML'),
-  HTMLElement_insertAdjacentElement: window.HTMLElement.prototype['insertAdjacentElement'],
-};
-
-/**
- * This class exists only to work around Closure's lack of a way to describe
- * singletons. It represents the 'already constructed marker' used in custom
- * element construction stacks.
- *
- * https://html.spec.whatwg.org/#concept-already-constructed-marker
- */
-class AlreadyConstructedMarker {}
-
-var AlreadyConstructedMarker$1 = new AlreadyConstructedMarker();
-
-/**
- * @param {!CustomElementInternals} internals
- */
-var PatchHTMLElement = function(internals) {
-  window['HTMLElement'] = (function() {
-    /**
-     * @type {function(new: HTMLElement): !HTMLElement}
-     */
-    function HTMLElement() {
-      // This should really be `new.target` but `new.target` can't be emulated
-      // in ES5. Assuming the user keeps the default value of the constructor's
-      // prototype's `constructor` property, this is equivalent.
-      /** @type {!Function} */
-      const constructor = this.constructor;
-
-      const definition = internals.constructorToDefinition(constructor);
-      if (!definition) {
-        throw new Error('The custom element being constructed was not registered with `customElements`.');
-      }
-
-      const constructionStack = definition.constructionStack;
-
-      if (constructionStack.length === 0) {
-        const element = Native.Document_createElement.call(document, definition.localName);
-        Object.setPrototypeOf(element, constructor.prototype);
-        element.__CE_state = CustomElementState.custom;
-        element.__CE_definition = definition;
-        internals.patch(element);
-        return element;
-      }
-
-      const lastIndex = constructionStack.length - 1;
-      const element = constructionStack[lastIndex];
-      if (element === AlreadyConstructedMarker$1) {
-        throw new Error('The HTMLElement constructor was either called reentrantly for this constructor or called multiple times.');
-      }
-      constructionStack[lastIndex] = AlreadyConstructedMarker$1;
-
-      Object.setPrototypeOf(element, constructor.prototype);
-      internals.patch(/** @type {!HTMLElement} */ (element));
-
-      return element;
-    }
-
-    HTMLElement.prototype = Native.HTMLElement.prototype;
-
-    return HTMLElement;
-  })();
-};
-
-/**
- * @param {!CustomElementInternals} internals
- * @param {!Object} destination
- * @param {!ParentNodeNativeMethods} builtIn
- */
-var PatchParentNode = function(internals, destination, builtIn) {
-  /**
-   * @param {...(!Node|string)} nodes
-   */
-  destination['prepend'] = function(...nodes) {
-    // TODO: Fix this for when one of `nodes` is a DocumentFragment!
-    const connectedBefore = /** @type {!Array<!Node>} */ (nodes.filter(node => {
-      // DocumentFragments are not connected and will not be added to the list.
-      return node instanceof Node && isConnected(node);
-    }));
-
-    builtIn.prepend.apply(this, nodes);
-
-    for (let i = 0; i < connectedBefore.length; i++) {
-      internals.disconnectTree(connectedBefore[i]);
-    }
-
-    if (isConnected(this)) {
-      for (let i = 0; i < nodes.length; i++) {
-        const node = nodes[i];
-        if (node instanceof Element) {
-          internals.connectTree(node);
-        }
-      }
-    }
-  };
-
-  /**
-   * @param {...(!Node|string)} nodes
-   */
-  destination['append'] = function(...nodes) {
-    // TODO: Fix this for when one of `nodes` is a DocumentFragment!
-    const connectedBefore = /** @type {!Array<!Node>} */ (nodes.filter(node => {
-      // DocumentFragments are not connected and will not be added to the list.
-      return node instanceof Node && isConnected(node);
-    }));
-
-    builtIn.append.apply(this, nodes);
-
-    for (let i = 0; i < connectedBefore.length; i++) {
-      internals.disconnectTree(connectedBefore[i]);
-    }
-
-    if (isConnected(this)) {
-      for (let i = 0; i < nodes.length; i++) {
-        const node = nodes[i];
-        if (node instanceof Element) {
-          internals.connectTree(node);
-        }
-      }
-    }
-  };
-};
-
-/**
- * @param {!CustomElementInternals} internals
- */
-var PatchDocument = function(internals) {
-  setPropertyUnchecked(Document.prototype, 'createElement',
-    /**
-     * @this {Document}
-     * @param {string} localName
-     * @return {!Element}
-     */
-    function(localName) {
-      // Only create custom elements if this document is associated with the registry.
-      if (this.__CE_hasRegistry) {
-        const definition = internals.localNameToDefinition(localName);
-        if (definition) {
-          return new (definition.constructor)();
-        }
-      }
-
-      const result = /** @type {!Element} */
-        (Native.Document_createElement.call(this, localName));
-      internals.patch(result);
-      return result;
-    });
-
-  setPropertyUnchecked(Document.prototype, 'importNode',
-    /**
-     * @this {Document}
-     * @param {!Node} node
-     * @param {boolean=} deep
-     * @return {!Node}
-     */
-    function(node, deep) {
-      const clone = Native.Document_importNode.call(this, node, deep);
-      // Only create custom elements if this document is associated with the registry.
-      if (!this.__CE_hasRegistry) {
-        internals.patchTree(clone);
-      } else {
-        internals.patchAndUpgradeTree(clone);
-      }
-      return clone;
-    });
-
-  const NS_HTML = "http://www.w3.org/1999/xhtml";
-
-  setPropertyUnchecked(Document.prototype, 'createElementNS',
-    /**
-     * @this {Document}
-     * @param {?string} namespace
-     * @param {string} localName
-     * @return {!Element}
-     */
-    function(namespace, localName) {
-      // Only create custom elements if this document is associated with the registry.
-      if (this.__CE_hasRegistry && (namespace === null || namespace === NS_HTML)) {
-        const definition = internals.localNameToDefinition(localName);
-        if (definition) {
-          return new (definition.constructor)();
-        }
-      }
-
-      const result = /** @type {!Element} */
-        (Native.Document_createElementNS.call(this, namespace, localName));
-      internals.patch(result);
-      return result;
-    });
-
-  PatchParentNode(internals, Document.prototype, {
-    prepend: Native.Document_prepend,
-    append: Native.Document_append,
-  });
-};
-
-/**
- * @param {!CustomElementInternals} internals
- */
-var PatchNode = function(internals) {
-  // `Node#nodeValue` is implemented on `Attr`.
-  // `Node#textContent` is implemented on `Attr`, `Element`.
-
-  setPropertyUnchecked(Node.prototype, 'insertBefore',
-    /**
-     * @this {Node}
-     * @param {!Node} node
-     * @param {?Node} refNode
-     * @return {!Node}
-     */
-    function(node, refNode) {
-      if (node instanceof DocumentFragment) {
-        const insertedNodes = Array.prototype.slice.apply(node.childNodes);
-        const nativeResult = Native.Node_insertBefore.call(this, node, refNode);
-
-        // DocumentFragments can't be connected, so `disconnectTree` will never
-        // need to be called on a DocumentFragment's children after inserting it.
-
-        if (isConnected(this)) {
-          for (let i = 0; i < insertedNodes.length; i++) {
-            internals.connectTree(insertedNodes[i]);
-          }
-        }
-
-        return nativeResult;
-      }
-
-      const nodeWasConnected = isConnected(node);
-      const nativeResult = Native.Node_insertBefore.call(this, node, refNode);
-
-      if (nodeWasConnected) {
-        internals.disconnectTree(node);
-      }
-
-      if (isConnected(this)) {
-        internals.connectTree(node);
-      }
-
-      return nativeResult;
-    });
-
-  setPropertyUnchecked(Node.prototype, 'appendChild',
-    /**
-     * @this {Node}
-     * @param {!Node} node
-     * @return {!Node}
-     */
-    function(node) {
-      if (node instanceof DocumentFragment) {
-        const insertedNodes = Array.prototype.slice.apply(node.childNodes);
-        const nativeResult = Native.Node_appendChild.call(this, node);
-
-        // DocumentFragments can't be connected, so `disconnectTree` will never
-        // need to be called on a DocumentFragment's children after inserting it.
-
-        if (isConnected(this)) {
-          for (let i = 0; i < insertedNodes.length; i++) {
-            internals.connectTree(insertedNodes[i]);
-          }
-        }
-
-        return nativeResult;
-      }
-
-      const nodeWasConnected = isConnected(node);
-      const nativeResult = Native.Node_appendChild.call(this, node);
-
-      if (nodeWasConnected) {
-        internals.disconnectTree(node);
-      }
-
-      if (isConnected(this)) {
-        internals.connectTree(node);
-      }
-
-      return nativeResult;
-    });
-
-  setPropertyUnchecked(Node.prototype, 'cloneNode',
-    /**
-     * @this {Node}
-     * @param {boolean=} deep
-     * @return {!Node}
-     */
-    function(deep) {
-      const clone = Native.Node_cloneNode.call(this, deep);
-      // Only create custom elements if this element's owner document is
-      // associated with the registry.
-      if (!this.ownerDocument.__CE_hasRegistry) {
-        internals.patchTree(clone);
-      } else {
-        internals.patchAndUpgradeTree(clone);
-      }
-      return clone;
-    });
-
-  setPropertyUnchecked(Node.prototype, 'removeChild',
-    /**
-     * @this {Node}
-     * @param {!Node} node
-     * @return {!Node}
-     */
-    function(node) {
-      const nodeWasConnected = isConnected(node);
-      const nativeResult = Native.Node_removeChild.call(this, node);
-
-      if (nodeWasConnected) {
-        internals.disconnectTree(node);
-      }
-
-      return nativeResult;
-    });
-
-  setPropertyUnchecked(Node.prototype, 'replaceChild',
-    /**
-     * @this {Node}
-     * @param {!Node} nodeToInsert
-     * @param {!Node} nodeToRemove
-     * @return {!Node}
-     */
-    function(nodeToInsert, nodeToRemove) {
-      if (nodeToInsert instanceof DocumentFragment) {
-        const insertedNodes = Array.prototype.slice.apply(nodeToInsert.childNodes);
-        const nativeResult = Native.Node_replaceChild.call(this, nodeToInsert, nodeToRemove);
-
-        // DocumentFragments can't be connected, so `disconnectTree` will never
-        // need to be called on a DocumentFragment's children after inserting it.
-
-        if (isConnected(this)) {
-          internals.disconnectTree(nodeToRemove);
-          for (let i = 0; i < insertedNodes.length; i++) {
-            internals.connectTree(insertedNodes[i]);
-          }
-        }
-
-        return nativeResult;
-      }
-
-      const nodeToInsertWasConnected = isConnected(nodeToInsert);
-      const nativeResult = Native.Node_replaceChild.call(this, nodeToInsert, nodeToRemove);
-      const thisIsConnected = isConnected(this);
-
-      if (thisIsConnected) {
-        internals.disconnectTree(nodeToRemove);
-      }
-
-      if (nodeToInsertWasConnected) {
-        internals.disconnectTree(nodeToInsert);
-      }
-
-      if (thisIsConnected) {
-        internals.connectTree(nodeToInsert);
-      }
-
-      return nativeResult;
-    });
-
-
-  function patch_textContent(destination, baseDescriptor) {
-    Object.defineProperty(destination, 'textContent', {
-      enumerable: baseDescriptor.enumerable,
-      configurable: true,
-      get: baseDescriptor.get,
-      set: /** @this {Node} */ function(assignedValue) {
-        // If this is a text node then there are no nodes to disconnect.
-        if (this.nodeType === Node.TEXT_NODE) {
-          baseDescriptor.set.call(this, assignedValue);
-          return;
-        }
-
-        let removedNodes = undefined;
-        // Checking for `firstChild` is faster than reading `childNodes.length`
-        // to compare with 0.
-        if (this.firstChild) {
-          // Using `childNodes` is faster than `children`, even though we only
-          // care about elements.
-          const childNodes = this.childNodes;
-          const childNodesLength = childNodes.length;
-          if (childNodesLength > 0 && isConnected(this)) {
-            // Copying an array by iterating is faster than using slice.
-            removedNodes = new Array(childNodesLength);
-            for (let i = 0; i < childNodesLength; i++) {
-              removedNodes[i] = childNodes[i];
-            }
-          }
-        }
-
-        baseDescriptor.set.call(this, assignedValue);
-
-        if (removedNodes) {
-          for (let i = 0; i < removedNodes.length; i++) {
-            internals.disconnectTree(removedNodes[i]);
-          }
-        }
-      },
-    });
-  }
-
-  if (Native.Node_textContent && Native.Node_textContent.get) {
-    patch_textContent(Node.prototype, Native.Node_textContent);
-  } else {
-    internals.addPatch(function(element) {
-      patch_textContent(element, {
-        enumerable: true,
-        configurable: true,
-        // NOTE: This implementation of the `textContent` getter assumes that
-        // text nodes' `textContent` getter will not be patched.
-        get: /** @this {Node} */ function() {
-          /** @type {!Array<string>} */
-          const parts = [];
-
-          for (let i = 0; i < this.childNodes.length; i++) {
-            parts.push(this.childNodes[i].textContent);
-          }
-
-          return parts.join('');
-        },
-        set: /** @this {Node} */ function(assignedValue) {
-          while (this.firstChild) {
-            Native.Node_removeChild.call(this, this.firstChild);
-          }
-          Native.Node_appendChild.call(this, document.createTextNode(assignedValue));
-        },
-      });
-    });
-  }
-};
-
-/**
- * @param {!CustomElementInternals} internals
- * @param {!Object} destination
- * @param {!ChildNodeNativeMethods} builtIn
- */
-var PatchChildNode = function(internals, destination, builtIn) {
-  /**
-   * @param {...(!Node|string)} nodes
-   */
-  destination['before'] = function(...nodes) {
-    // TODO: Fix this for when one of `nodes` is a DocumentFragment!
-    const connectedBefore = /** @type {!Array<!Node>} */ (nodes.filter(node => {
-      // DocumentFragments are not connected and will not be added to the list.
-      return node instanceof Node && isConnected(node);
-    }));
-
-    builtIn.before.apply(this, nodes);
-
-    for (let i = 0; i < connectedBefore.length; i++) {
-      internals.disconnectTree(connectedBefore[i]);
-    }
-
-    if (isConnected(this)) {
-      for (let i = 0; i < nodes.length; i++) {
-        const node = nodes[i];
-        if (node instanceof Element) {
-          internals.connectTree(node);
-        }
-      }
-    }
-  };
-
-  /**
-   * @param {...(!Node|string)} nodes
-   */
-  destination['after'] = function(...nodes) {
-    // TODO: Fix this for when one of `nodes` is a DocumentFragment!
-    const connectedBefore = /** @type {!Array<!Node>} */ (nodes.filter(node => {
-      // DocumentFragments are not connected and will not be added to the list.
-      return node instanceof Node && isConnected(node);
-    }));
-
-    builtIn.after.apply(this, nodes);
-
-    for (let i = 0; i < connectedBefore.length; i++) {
-      internals.disconnectTree(connectedBefore[i]);
-    }
-
-    if (isConnected(this)) {
-      for (let i = 0; i < nodes.length; i++) {
-        const node = nodes[i];
-        if (node instanceof Element) {
-          internals.connectTree(node);
-        }
-      }
-    }
-  };
-
-  /**
-   * @param {...(!Node|string)} nodes
-   */
-  destination['replaceWith'] = function(...nodes) {
-    // TODO: Fix this for when one of `nodes` is a DocumentFragment!
-    const connectedBefore = /** @type {!Array<!Node>} */ (nodes.filter(node => {
-      // DocumentFragments are not connected and will not be added to the list.
-      return node instanceof Node && isConnected(node);
-    }));
-
-    const wasConnected = isConnected(this);
-
-    builtIn.replaceWith.apply(this, nodes);
-
-    for (let i = 0; i < connectedBefore.length; i++) {
-      internals.disconnectTree(connectedBefore[i]);
-    }
-
-    if (wasConnected) {
-      internals.disconnectTree(this);
-      for (let i = 0; i < nodes.length; i++) {
-        const node = nodes[i];
-        if (node instanceof Element) {
-          internals.connectTree(node);
-        }
-      }
-    }
-  };
-
-  destination['remove'] = function() {
-    const wasConnected = isConnected(this);
-
-    builtIn.remove.call(this);
-
-    if (wasConnected) {
-      internals.disconnectTree(this);
-    }
-  };
-};
-
-/**
- * @param {!CustomElementInternals} internals
- */
-var PatchElement = function(internals) {
-  if (Native.Element_attachShadow) {
-    setPropertyUnchecked(Element.prototype, 'attachShadow',
-      /**
-       * @this {Element}
-       * @param {!{mode: string}} init
-       * @return {ShadowRoot}
-       */
-      function(init) {
-        const shadowRoot = Native.Element_attachShadow.call(this, init);
-        this.__CE_shadowRoot = shadowRoot;
-        return shadowRoot;
-      });
-  } else {
-    console.warn('Custom Elements: `Element#attachShadow` was not patched.');
-  }
-
-
-  function patch_innerHTML(destination, baseDescriptor) {
-    Object.defineProperty(destination, 'innerHTML', {
-      enumerable: baseDescriptor.enumerable,
-      configurable: true,
-      get: baseDescriptor.get,
-      set: /** @this {Element} */ function(htmlString) {
-        const isConnected$$1 = isConnected(this);
-
-        // NOTE: In IE11, when using the native `innerHTML` setter, all nodes
-        // that were previously descendants of the context element have all of
-        // their children removed as part of the set - the entire subtree is
-        // 'disassembled'. This work around walks the subtree *before* using the
-        // native setter.
-        /** @type {!Array<!Element>|undefined} */
-        let removedElements = undefined;
-        if (isConnected$$1) {
-          removedElements = [];
-          walkDeepDescendantElements(this, element => {
-            if (element !== this) {
-              removedElements.push(element);
-            }
-          });
-        }
-
-        baseDescriptor.set.call(this, htmlString);
-
-        if (removedElements) {
-          for (let i = 0; i < removedElements.length; i++) {
-            const element = removedElements[i];
-            if (element.__CE_state === CustomElementState.custom) {
-              internals.disconnectedCallback(element);
-            }
-          }
-        }
-
-        // Only create custom elements if this element's owner document is
-        // associated with the registry.
-        if (!this.ownerDocument.__CE_hasRegistry) {
-          internals.patchTree(this);
-        } else {
-          internals.patchAndUpgradeTree(this);
-        }
-        return htmlString;
-      },
-    });
-  }
-
-  if (Native.Element_innerHTML && Native.Element_innerHTML.get) {
-    patch_innerHTML(Element.prototype, Native.Element_innerHTML);
-  } else if (Native.HTMLElement_innerHTML && Native.HTMLElement_innerHTML.get) {
-    patch_innerHTML(HTMLElement.prototype, Native.HTMLElement_innerHTML);
-  } else {
-
-    /** @type {HTMLDivElement} */
-    const rawDiv = Native.Document_createElement.call(document, 'div');
-
-    internals.addPatch(function(element) {
-      patch_innerHTML(element, {
-        enumerable: true,
-        configurable: true,
-        // Implements getting `innerHTML` by performing an unpatched `cloneNode`
-        // of the element and returning the resulting element's `innerHTML`.
-        // TODO: Is this too expensive?
-        get: /** @this {Element} */ function() {
-          return Native.Node_cloneNode.call(this, true).innerHTML;
-        },
-        // Implements setting `innerHTML` by creating an unpatched element,
-        // setting `innerHTML` of that element and replacing the target
-        // element's children with those of the unpatched element.
-        set: /** @this {Element} */ function(assignedValue) {
-          // NOTE: re-route to `content` for `template` elements.
-          // We need to do this because `template.appendChild` does not
-          // route into `template.content`.
-          /** @type {!Node} */
-          const content = this.localName === 'template' ? (/** @type {!HTMLTemplateElement} */ (this)).content : this;
-          rawDiv.innerHTML = assignedValue;
-
-          while (content.childNodes.length > 0) {
-            Native.Node_removeChild.call(content, content.childNodes[0]);
-          }
-          while (rawDiv.childNodes.length > 0) {
-            Native.Node_appendChild.call(content, rawDiv.childNodes[0]);
-          }
-        },
-      });
-    });
-  }
-
-
-  setPropertyUnchecked(Element.prototype, 'setAttribute',
-    /**
-     * @this {Element}
-     * @param {string} name
-     * @param {string} newValue
-     */
-    function(name, newValue) {
-      // Fast path for non-custom elements.
-      if (this.__CE_state !== CustomElementState.custom) {
-        return Native.Element_setAttribute.call(this, name, newValue);
-      }
-
-      const oldValue = Native.Element_getAttribute.call(this, name);
-      Native.Element_setAttribute.call(this, name, newValue);
-      newValue = Native.Element_getAttribute.call(this, name);
-      if (oldValue !== newValue) {
-        internals.attributeChangedCallback(this, name, oldValue, newValue, null);
-      }
-    });
-
-  setPropertyUnchecked(Element.prototype, 'setAttributeNS',
-    /**
-     * @this {Element}
-     * @param {?string} namespace
-     * @param {string} name
-     * @param {string} newValue
-     */
-    function(namespace, name, newValue) {
-      // Fast path for non-custom elements.
-      if (this.__CE_state !== CustomElementState.custom) {
-        return Native.Element_setAttributeNS.call(this, namespace, name, newValue);
-      }
-
-      const oldValue = Native.Element_getAttributeNS.call(this, namespace, name);
-      Native.Element_setAttributeNS.call(this, namespace, name, newValue);
-      newValue = Native.Element_getAttributeNS.call(this, namespace, name);
-      if (oldValue !== newValue) {
-        internals.attributeChangedCallback(this, name, oldValue, newValue, namespace);
-      }
-    });
-
-  setPropertyUnchecked(Element.prototype, 'removeAttribute',
-    /**
-     * @this {Element}
-     * @param {string} name
-     */
-    function(name) {
-      // Fast path for non-custom elements.
-      if (this.__CE_state !== CustomElementState.custom) {
-        return Native.Element_removeAttribute.call(this, name);
-      }
-
-      const oldValue = Native.Element_getAttribute.call(this, name);
-      Native.Element_removeAttribute.call(this, name);
-      if (oldValue !== null) {
-        internals.attributeChangedCallback(this, name, oldValue, null, null);
-      }
-    });
-
-  setPropertyUnchecked(Element.prototype, 'removeAttributeNS',
-    /**
-     * @this {Element}
-     * @param {?string} namespace
-     * @param {string} name
-     */
-    function(namespace, name) {
-      // Fast path for non-custom elements.
-      if (this.__CE_state !== CustomElementState.custom) {
-        return Native.Element_removeAttributeNS.call(this, namespace, name);
-      }
-
-      const oldValue = Native.Element_getAttributeNS.call(this, namespace, name);
-      Native.Element_removeAttributeNS.call(this, namespace, name);
-      // In older browsers, `Element#getAttributeNS` may return the empty string
-      // instead of null if the attribute does not exist. For details, see;
-      // https://developer.mozilla.org/en-US/docs/Web/API/Element/getAttributeNS#Notes
-      const newValue = Native.Element_getAttributeNS.call(this, namespace, name);
-      if (oldValue !== newValue) {
-        internals.attributeChangedCallback(this, name, oldValue, newValue, namespace);
-      }
-    });
-
-
-  function patch_insertAdjacentElement(destination, baseMethod) {
-    setPropertyUnchecked(destination, 'insertAdjacentElement',
-      /**
-       * @this {Element}
-       * @param {string} where
-       * @param {!Element} element
-       * @return {?Element}
-       */
-      function(where, element) {
-        const wasConnected = isConnected(element);
-        const insertedElement = /** @type {!Element} */
-          (baseMethod.call(this, where, element));
-
-        if (wasConnected) {
-          internals.disconnectTree(element);
-        }
-
-        if (isConnected(insertedElement)) {
-          internals.connectTree(element);
-        }
-        return insertedElement;
-      });
-  }
-
-  if (Native.HTMLElement_insertAdjacentElement) {
-    patch_insertAdjacentElement(HTMLElement.prototype, Native.HTMLElement_insertAdjacentElement);
-  } else if (Native.Element_insertAdjacentElement) {
-    patch_insertAdjacentElement(Element.prototype, Native.Element_insertAdjacentElement);
-  } else {
-    console.warn('Custom Elements: `Element#insertAdjacentElement` was not patched.');
-  }
-
-
-  PatchParentNode(internals, Element.prototype, {
-    prepend: Native.Element_prepend,
-    append: Native.Element_append,
-  });
-
-  PatchChildNode(internals, Element.prototype, {
-    before: Native.Element_before,
-    after: Native.Element_after,
-    replaceWith: Native.Element_replaceWith,
-    remove: Native.Element_remove,
-  });
-};
-
-/**
- * @license
- * Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
- * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
- * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
- * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
- * Code distributed by Google as part of the polymer project is also
- * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
- */
-
-const priorCustomElements = window['customElements'];
-
-if (!priorCustomElements ||
-     priorCustomElements['forcePolyfill'] ||
-     (typeof priorCustomElements['define'] != 'function') ||
-     (typeof priorCustomElements['get'] != 'function')) {
-  /** @type {!CustomElementInternals} */
-  const internals = new CustomElementInternals();
-
-  PatchHTMLElement(internals);
-  PatchDocument(internals);
-  PatchNode(internals);
-  PatchElement(internals);
-
-  // The main document is always associated with the registry.
-  document.__CE_hasRegistry = true;
-
-  /** @type {!CustomElementRegistry} */
-  const customElements = new CustomElementRegistry(internals);
-
-  Object.defineProperty(window, 'customElements', {
-    configurable: true,
-    enumerable: true,
-    value: customElements,
-  });
-}
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/*
-Extremely simple css parser. Intended to be not more than what we need
-and definitely not necessarily correct =).
-*/
-
-/** @unrestricted */
-class StyleNode {
-  constructor() {
-    /** @type {number} */
-    this['start'] = 0;
-    /** @type {number} */
-    this['end'] = 0;
-    /** @type {StyleNode} */
-    this['previous'] = null;
-    /** @type {StyleNode} */
-    this['parent'] = null;
-    /** @type {Array<StyleNode>} */
-    this['rules'] = null;
-    /** @type {string} */
-    this['parsedCssText'] = '';
-    /** @type {string} */
-    this['cssText'] = '';
-    /** @type {boolean} */
-    this['atRule'] = false;
-    /** @type {number} */
-    this['type'] = 0;
-    /** @type {string} */
-    this['keyframesName'] = '';
-    /** @type {string} */
-    this['selector'] = '';
-    /** @type {string} */
-    this['parsedSelector'] = '';
-  }
-}
-
-// given a string of css, return a simple rule tree
-/**
- * @param {string} text
- * @return {StyleNode}
- */
-function parse(text) {
-  text = clean(text);
-  return parseCss(lex(text), text);
-}
-
-// remove stuff we don't care about that may hinder parsing
-/**
- * @param {string} cssText
- * @return {string}
- */
-function clean(cssText) {
-  return cssText.replace(RX.comments, '').replace(RX.port, '');
-}
-
-// super simple {...} lexer that returns a node tree
-/**
- * @param {string} text
- * @return {StyleNode}
- */
-function lex(text) {
-  let root = new StyleNode();
-  root['start'] = 0;
-  root['end'] = text.length;
-  let n = root;
-  for (let i = 0, l = text.length; i < l; i++) {
-    if (text[i] === OPEN_BRACE) {
-      if (!n['rules']) {
-        n['rules'] = [];
-      }
-      let p = n;
-      let previous = p['rules'][p['rules'].length - 1] || null;
-      n = new StyleNode();
-      n['start'] = i + 1;
-      n['parent'] = p;
-      n['previous'] = previous;
-      p['rules'].push(n);
-    } else if (text[i] === CLOSE_BRACE) {
-      n['end'] = i + 1;
-      n = n['parent'] || root;
-    }
-  }
-  return root;
-}
-
-// add selectors/cssText to node tree
-/**
- * @param {StyleNode} node
- * @param {string} text
- * @return {StyleNode}
- */
-function parseCss(node, text) {
-  let t = text.substring(node['start'], node['end'] - 1);
-  node['parsedCssText'] = node['cssText'] = t.trim();
-  if (node['parent']) {
-    let ss = node['previous'] ? node['previous']['end'] : node['parent']['start'];
-    t = text.substring(ss, node['start'] - 1);
-    t = _expandUnicodeEscapes(t);
-    t = t.replace(RX.multipleSpaces, ' ');
-    // TODO(sorvell): ad hoc; make selector include only after last ;
-    // helps with mixin syntax
-    t = t.substring(t.lastIndexOf(';') + 1);
-    let s = node['parsedSelector'] = node['selector'] = t.trim();
-    node['atRule'] = (s.indexOf(AT_START) === 0);
-    // note, support a subset of rule types...
-    if (node['atRule']) {
-      if (s.indexOf(MEDIA_START) === 0) {
-        node['type'] = types.MEDIA_RULE;
-      } else if (s.match(RX.keyframesRule)) {
-        node['type'] = types.KEYFRAMES_RULE;
-        node['keyframesName'] =
-          node['selector'].split(RX.multipleSpaces).pop();
-      }
-    } else {
-      if (s.indexOf(VAR_START) === 0) {
-        node['type'] = types.MIXIN_RULE;
-      } else {
-        node['type'] = types.STYLE_RULE;
-      }
-    }
-  }
-  let r$ = node['rules'];
-  if (r$) {
-    for (let i = 0, l = r$.length, r;
-      (i < l) && (r = r$[i]); i++) {
-      parseCss(r, text);
-    }
-  }
-  return node;
-}
-
-/**
- * conversion of sort unicode escapes with spaces like `\33 ` (and longer) into
- * expanded form that doesn't require trailing space `\000033`
- * @param {string} s
- * @return {string}
- */
-function _expandUnicodeEscapes(s) {
-  return s.replace(/\\([0-9a-f]{1,6})\s/gi, function() {
-    let code = arguments[1],
-      repeat = 6 - code.length;
-    while (repeat--) {
-      code = '0' + code;
-    }
-    return '\\' + code;
-  });
-}
-
-/**
- * stringify parsed css.
- * @param {StyleNode} node
- * @param {boolean=} preserveProperties
- * @param {string=} text
- * @return {string}
- */
-function stringify(node, preserveProperties, text = '') {
-  // calc rule cssText
-  let cssText = '';
-  if (node['cssText'] || node['rules']) {
-    let r$ = node['rules'];
-    if (r$ && !_hasMixinRules(r$)) {
-      for (let i = 0, l = r$.length, r;
-        (i < l) && (r = r$[i]); i++) {
-        cssText = stringify(r, preserveProperties, cssText);
-      }
-    } else {
-      cssText = preserveProperties ? node['cssText'] :
-        removeCustomProps(node['cssText']);
-      cssText = cssText.trim();
-      if (cssText) {
-        cssText = '  ' + cssText + '\n';
-      }
-    }
-  }
-  // emit rule if there is cssText
-  if (cssText) {
-    if (node['selector']) {
-      text += node['selector'] + ' ' + OPEN_BRACE + '\n';
-    }
-    text += cssText;
-    if (node['selector']) {
-      text += CLOSE_BRACE + '\n\n';
-    }
-  }
-  return text;
-}
-
-/**
- * @param {Array<StyleNode>} rules
- * @return {boolean}
- */
-function _hasMixinRules(rules) {
-  let r = rules[0];
-  return Boolean(r) && Boolean(r['selector']) && r['selector'].indexOf(VAR_START) === 0;
-}
-
-/**
- * @param {string} cssText
- * @return {string}
- */
-function removeCustomProps(cssText) {
-  cssText = removeCustomPropAssignment(cssText);
-  return removeCustomPropApply(cssText);
-}
-
-/**
- * @param {string} cssText
- * @return {string}
- */
-function removeCustomPropAssignment(cssText) {
-  return cssText
-    .replace(RX.customProp, '')
-    .replace(RX.mixinProp, '');
-}
-
-/**
- * @param {string} cssText
- * @return {string}
- */
-function removeCustomPropApply(cssText) {
-  return cssText
-    .replace(RX.mixinApply, '')
-    .replace(RX.varApply, '');
-}
-
-/** @enum {number} */
-const types = {
-  STYLE_RULE: 1,
-  KEYFRAMES_RULE: 7,
-  MEDIA_RULE: 4,
-  MIXIN_RULE: 1000
-};
-
-const OPEN_BRACE = '{';
-const CLOSE_BRACE = '}';
-
-// helper regexp's
-const RX = {
-  comments: /\/\*[^*]*\*+([^/*][^*]*\*+)*\//gim,
-  port: /@import[^;]*;/gim,
-  customProp: /(?:^[^;\-\s}]+)?--[^;{}]*?:[^{};]*?(?:[;\n]|$)/gim,
-  mixinProp: /(?:^[^;\-\s}]+)?--[^;{}]*?:[^{};]*?{[^}]*?}(?:[;\n]|$)?/gim,
-  mixinApply: /@apply\s*\(?[^);]*\)?\s*(?:[;\n]|$)?/gim,
-  varApply: /[^;:]*?:[^;]*?var\([^;]*\)(?:[;\n]|$)?/gim,
-  keyframesRule: /^@[^\s]*keyframes/,
-  multipleSpaces: /\s+/g
-};
-
-const VAR_START = '--';
-const MEDIA_START = '@media';
-const AT_START = '@';
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-let nativeShadow = !(window['ShadyDOM'] && window['ShadyDOM']['inUse']);
-// chrome 49 has semi-working css vars, check if box-shadow works
-// safari 9.1 has a recalc bug: https://bugs.webkit.org/show_bug.cgi?id=155782
-let nativeCssVariables = (!navigator.userAgent.match('AppleWebKit/601') &&
-window.CSS && CSS.supports && CSS.supports('box-shadow', '0 0 0 var(--foo)'));
-
-/**
- * @param {ShadyCSSOptions | ShadyCSSInterface | undefined} settings
- */
-function parseSettings(settings) {
-  if (settings) {
-    nativeCssVariables = nativeCssVariables && !settings['nativeCss'] && !settings['shimcssproperties'];
-  nativeShadow = nativeShadow && !settings['nativeShadow'] && !settings['shimshadow'];
-  }
-}
-
-if (window.ShadyCSS) {
-  parseSettings(window.ShadyCSS);
-} else if (window['WebComponents']) {
-  parseSettings(window['WebComponents']['flags']);
-}
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-const VAR_ASSIGN = /(?:^|[;\s{]\s*)(--[\w-]*?)\s*:\s*(?:([^;{]*)|{([^}]*)})(?:(?=[;\s}])|$)/gi;
-const MIXIN_MATCH = /(?:^|\W+)@apply\s*\(?([^);\n]*)\)?/gi;
-const VAR_CONSUMED = /(--[\w-]+)\s*([:,;)]|$)/gi;
-const ANIMATION_MATCH = /(animation\s*:)|(animation-name\s*:)/;
-const MEDIA_MATCH = /@media[^(]*(\([^)]*\))/;
-
-const BRACKETED = /\{[^}]*\}/g;
-const HOST_PREFIX = '(?:^|[^.#[:])';
-const HOST_SUFFIX = '($|[.:[\\s>+~])';
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/**
- * @param {string|StyleNode} rules
- * @param {function(StyleNode)=} callback
- * @return {string}
- */
-function toCssText (rules, callback) {
-  if (!rules) {
-    return '';
-  }
-  if (typeof rules === 'string') {
-    rules = parse(rules);
-  }
-  if (callback) {
-    forEachRule(rules, callback);
-  }
-  return stringify(rules, nativeCssVariables);
-}
-
-/**
- * @param {HTMLStyleElement} style
- * @return {StyleNode}
- */
-function rulesForStyle(style) {
-  if (!style['__cssRules'] && style.textContent) {
-    style['__cssRules'] = parse(style.textContent);
-  }
-  return style['__cssRules'] || null;
-}
-
-// Tests if a rule is a keyframes selector, which looks almost exactly
-// like a normal selector but is not (it has nothing to do with scoping
-// for example).
-/**
- * @param {StyleNode} rule
- * @return {boolean}
- */
-function isKeyframesSelector(rule) {
-  return Boolean(rule['parent']) &&
-  rule['parent']['type'] === types.KEYFRAMES_RULE;
-}
-
-/**
- * @param {StyleNode} node
- * @param {Function=} styleRuleCallback
- * @param {Function=} keyframesRuleCallback
- * @param {boolean=} onlyActiveRules
- */
-function forEachRule(node, styleRuleCallback, keyframesRuleCallback, onlyActiveRules) {
-  if (!node) {
-    return;
-  }
-  let skipRules = false;
-  let type = node['type'];
-  if (onlyActiveRules) {
-    if (type === types.MEDIA_RULE) {
-      let matchMedia = node['selector'].match(MEDIA_MATCH);
-      if (matchMedia) {
-        // if rule is a non matching @media rule, skip subrules
-        if (!window.matchMedia(matchMedia[1]).matches) {
-          skipRules = true;
-        }
-      }
-    }
-  }
-  if (type === types.STYLE_RULE) {
-    styleRuleCallback(node);
-  } else if (keyframesRuleCallback &&
-    type === types.KEYFRAMES_RULE) {
-    keyframesRuleCallback(node);
-  } else if (type === types.MIXIN_RULE) {
-    skipRules = true;
-  }
-  let r$ = node['rules'];
-  if (r$ && !skipRules) {
-    for (let i=0, l=r$.length, r; (i<l) && (r=r$[i]); i++) {
-      forEachRule(r, styleRuleCallback, keyframesRuleCallback, onlyActiveRules);
-    }
-  }
-}
-
-// add a string of cssText to the document.
-/**
- * @param {string} cssText
- * @param {string} moniker
- * @param {Node} target
- * @param {Node} contextNode
- * @return {HTMLStyleElement}
- */
-function applyCss(cssText, moniker, target, contextNode) {
-  let style = createScopeStyle(cssText, moniker);
-  applyStyle(style, target, contextNode);
-  return style;
-}
-
-/**
- * @param {string} cssText
- * @param {string} moniker
- * @return {HTMLStyleElement}
- */
-function createScopeStyle(cssText, moniker) {
-  let style = /** @type {HTMLStyleElement} */(document.createElement('style'));
-  if (moniker) {
-    style.setAttribute('scope', moniker);
-  }
-  style.textContent = cssText;
-  return style;
-}
-
-/**
- * Track the position of the last added style for placing placeholders
- * @type {Node}
- */
-let lastHeadApplyNode = null;
-
-// insert a comment node as a styling position placeholder.
-/**
- * @param {string} moniker
- * @return {!Comment}
- */
-function applyStylePlaceHolder(moniker) {
-  let placeHolder = document.createComment(' Shady DOM styles for ' +
-    moniker + ' ');
-  let after = lastHeadApplyNode ?
-    lastHeadApplyNode['nextSibling'] : null;
-  let scope = document.head;
-  scope.insertBefore(placeHolder, after || scope.firstChild);
-  lastHeadApplyNode = placeHolder;
-  return placeHolder;
-}
-
-/**
- * @param {HTMLStyleElement} style
- * @param {?Node} target
- * @param {?Node} contextNode
- */
-function applyStyle(style, target, contextNode) {
-  target = target || document.head;
-  let after = (contextNode && contextNode.nextSibling) ||
-    target.firstChild;
-  target.insertBefore(style, after);
-  if (!lastHeadApplyNode) {
-    lastHeadApplyNode = style;
-  } else {
-    // only update lastHeadApplyNode if the new style is inserted after the old lastHeadApplyNode
-    let position = style.compareDocumentPosition(lastHeadApplyNode);
-    if (position === Node.DOCUMENT_POSITION_PRECEDING) {
-      lastHeadApplyNode = style;
-    }
-  }
-}
-
-/**
- * @param {string} buildType
- * @return {boolean}
- */
-
-
-/**
- * @param {Element} element
- * @return {?string}
- */
-
-
-/**
- * Walk from text[start] matching parens and
- * returns position of the outer end paren
- * @param {string} text
- * @param {number} start
- * @return {number}
- */
-function findMatchingParen(text, start) {
-  let level = 0;
-  for (let i=start, l=text.length; i < l; i++) {
-    if (text[i] === '(') {
-      level++;
-    } else if (text[i] === ')') {
-      if (--level === 0) {
-        return i;
-      }
-    }
-  }
-  return -1;
-}
-
-/**
- * @param {string} str
- * @param {function(string, string, string, string)} callback
- */
-function processVariableAndFallback(str, callback) {
-  // find 'var('
-  let start = str.indexOf('var(');
-  if (start === -1) {
-    // no var?, everything is prefix
-    return callback(str, '', '', '');
-  }
-  //${prefix}var(${inner})${suffix}
-  let end = findMatchingParen(str, start + 3);
-  let inner = str.substring(start + 4, end);
-  let prefix = str.substring(0, start);
-  // suffix may have other variables
-  let suffix = processVariableAndFallback(str.substring(end + 1), callback);
-  let comma = inner.indexOf(',');
-  // value and fallback args should be trimmed to match in property lookup
-  if (comma === -1) {
-    // variable, no fallback
-    return callback(prefix, inner.trim(), '', suffix);
-  }
-  // var(${value},${fallback})
-  let value = inner.substring(0, comma).trim();
-  let fallback = inner.substring(comma + 1).trim();
-  return callback(prefix, value, fallback, suffix);
-}
-
-/**
- * @param {Element} element
- * @param {string} value
- */
-function setElementClassRaw(element, value) {
-  // use native setAttribute provided by ShadyDOM when setAttribute is patched
-  if (nativeShadow) {
-    element.setAttribute('class', value);
-  } else {
-    window['ShadyDOM']['nativeMethods']['setAttribute'].call(element, 'class', value);
-  }
-}
-
-/**
- * @param {Element | {is: string, extends: string}} element
- * @return {{is: string, typeExtension: string}}
- */
-function getIsExtends(element) {
-  let localName = element['localName'];
-  let is = '', typeExtension = '';
-  /*
-  NOTE: technically, this can be wrong for certain svg elements
-  with `-` in the name like `<font-face>`
-  */
-  if (localName) {
-    if (localName.indexOf('-') > -1) {
-      is = localName;
-    } else {
-      typeExtension = localName;
-      is = (element.getAttribute && element.getAttribute('is')) || '';
-    }
-  } else {
-    is = /** @type {?} */(element).is;
-    typeExtension = /** @type {?} */(element).extends;
-  }
-  return {is, typeExtension};
-}
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/* Transforms ShadowDOM styling into ShadyDOM styling
-
-* scoping:
-
-  * elements in scope get scoping selector class="x-foo-scope"
-  * selectors re-written as follows:
-
-    div button -> div.x-foo-scope button.x-foo-scope
-
-* :host -> scopeName
-
-* :host(...) -> scopeName...
-
-* ::slotted(...) -> scopeName > ...
-
-* ...:dir(ltr|rtl) -> [dir="ltr|rtl"] ..., ...[dir="ltr|rtl"]
-
-* :host(:dir[rtl]) -> scopeName:dir(rtl) -> [dir="rtl"] scopeName, scopeName[dir="rtl"]
-
-*/
-const SCOPE_NAME = 'style-scope';
-
-class StyleTransformer {
-  get SCOPE_NAME() {
-    return SCOPE_NAME;
-  }
-  // Given a node and scope name, add a scoping class to each node
-  // in the tree. This facilitates transforming css into scoped rules.
-  dom(node, scope, shouldRemoveScope) {
-    // one time optimization to skip scoping...
-    if (node['__styleScoped']) {
-      node['__styleScoped'] = null;
-    } else {
-      this._transformDom(node, scope || '', shouldRemoveScope);
-    }
-  }
-
-  _transformDom(node, selector, shouldRemoveScope) {
-    if (node.nodeType === Node.ELEMENT_NODE) {
-      this.element(node, selector, shouldRemoveScope);
-    }
-    let c$ = (node.localName === 'template') ?
-      (node.content || node._content).childNodes :
-      node.children || node.childNodes;
-    if (c$) {
-      for (let i=0; i<c$.length; i++) {
-        this._transformDom(c$[i], selector, shouldRemoveScope);
-      }
-    }
-  }
-
-  element(element, scope, shouldRemoveScope) {
-    // note: if using classes, we add both the general 'style-scope' class
-    // as well as the specific scope. This enables easy filtering of all
-    // `style-scope` elements
-    if (scope) {
-      // note: svg on IE does not have classList so fallback to class
-      if (element.classList) {
-        if (shouldRemoveScope) {
-          element.classList.remove(SCOPE_NAME);
-          element.classList.remove(scope);
-        } else {
-          element.classList.add(SCOPE_NAME);
-          element.classList.add(scope);
-        }
-      } else if (element.getAttribute) {
-        let c = element.getAttribute(CLASS);
-        if (shouldRemoveScope) {
-          if (c) {
-            let newValue = c.replace(SCOPE_NAME, '').replace(scope, '');
-            setElementClassRaw(element, newValue);
-          }
-        } else {
-          let newValue = (c ? c + ' ' : '') + SCOPE_NAME + ' ' + scope;
-          setElementClassRaw(element, newValue);
-        }
-      }
-    }
-  }
-
-  elementStyles(element, styleRules, callback) {
-    let cssBuildType = element['__cssBuild'];
-    // no need to shim selectors if settings.useNativeShadow, also
-    // a shady css build will already have transformed selectors
-    // NOTE: This method may be called as part of static or property shimming.
-    // When there is a targeted build it will not be called for static shimming,
-    // but when the property shim is used it is called and should opt out of
-    // static shimming work when a proper build exists.
-    let cssText = '';
-    if (nativeShadow || cssBuildType === 'shady') {
-      cssText = toCssText(styleRules, callback);
-    } else {
-      let {is, typeExtension} = getIsExtends(element);
-      cssText = this.css(styleRules, is, typeExtension, callback) + '\n\n';
-    }
-    return cssText.trim();
-  }
-
-  // Given a string of cssText and a scoping string (scope), returns
-  // a string of scoped css where each selector is transformed to include
-  // a class created from the scope. ShadowDOM selectors are also transformed
-  // (e.g. :host) to use the scoping selector.
-  css(rules, scope, ext, callback) {
-    let hostScope = this._calcHostScope(scope, ext);
-    scope = this._calcElementScope(scope);
-    let self = this;
-    return toCssText(rules, function(/** StyleNode */rule) {
-      if (!rule.isScoped) {
-        self.rule(rule, scope, hostScope);
-        rule.isScoped = true;
-      }
-      if (callback) {
-        callback(rule, scope, hostScope);
-      }
-    });
-  }
-
-  _calcElementScope(scope) {
-    if (scope) {
-      return CSS_CLASS_PREFIX + scope;
-    } else {
-      return '';
-    }
-  }
-
-  _calcHostScope(scope, ext) {
-    return ext ? `[is=${scope}]` : scope;
-  }
-
-  rule(rule, scope, hostScope) {
-    this._transformRule(rule, this._transformComplexSelector,
-      scope, hostScope);
-  }
-
-  /**
-   * transforms a css rule to a scoped rule.
-   *
-   * @param {StyleNode} rule
-   * @param {Function} transformer
-   * @param {string=} scope
-   * @param {string=} hostScope
-   */
-  _transformRule(rule, transformer, scope, hostScope) {
-    // NOTE: save transformedSelector for subsequent matching of elements
-    // against selectors (e.g. when calculating style properties)
-    rule['selector'] = rule.transformedSelector =
-      this._transformRuleCss(rule, transformer, scope, hostScope);
-  }
-
-  /**
-   * @param {StyleNode} rule
-   * @param {Function} transformer
-   * @param {string=} scope
-   * @param {string=} hostScope
-   */
-  _transformRuleCss(rule, transformer, scope, hostScope) {
-    let p$ = rule['selector'].split(COMPLEX_SELECTOR_SEP);
-    // we want to skip transformation of rules that appear in keyframes,
-    // because they are keyframe selectors, not element selectors.
-    if (!isKeyframesSelector(rule)) {
-      for (let i=0, l=p$.length, p; (i<l) && (p=p$[i]); i++) {
-        p$[i] = transformer.call(this, p, scope, hostScope);
-      }
-    }
-    return p$.join(COMPLEX_SELECTOR_SEP);
-  }
-
-/**
- * @param {string} selector
- * @param {string} scope
- * @param {string=} hostScope
- */
-  _transformComplexSelector(selector, scope, hostScope) {
-    let stop = false;
-    selector = selector.trim();
-    // Remove spaces inside of selectors like `:nth-of-type` because it confuses SIMPLE_SELECTOR_SEP
-    selector = selector.replace(NTH, (m, type, inner) => `:${type}(${inner.replace(/\s/g, '')})`);
-    selector = selector.replace(SLOTTED_START, `${HOST} $1`);
-    selector = selector.replace(SIMPLE_SELECTOR_SEP, (m, c, s) => {
-      if (!stop) {
-        let info = this._transformCompoundSelector(s, c, scope, hostScope);
-        stop = stop || info.stop;
-        c = info.combinator;
-        s = info.value;
-      }
-      return c + s;
-    });
-    return selector;
-  }
-
-  _transformCompoundSelector(selector, combinator, scope, hostScope) {
-    // replace :host with host scoping class
-    let slottedIndex = selector.indexOf(SLOTTED);
-    if (selector.indexOf(HOST) >= 0) {
-      selector = this._transformHostSelector(selector, hostScope);
-    // replace other selectors with scoping class
-    } else if (slottedIndex !== 0) {
-      selector = scope ? this._transformSimpleSelector(selector, scope) :
-        selector;
-    }
-    // mark ::slotted() scope jump to replace with descendant selector + arg
-    // also ignore left-side combinator
-    let slotted = false;
-    if (slottedIndex >= 0) {
-      combinator = '';
-      slotted = true;
-    }
-    // process scope jumping selectors up to the scope jump and then stop
-    let stop;
-    if (slotted) {
-      stop = true;
-      if (slotted) {
-        // .zonk ::slotted(.foo) -> .zonk.scope > .foo
-        selector = selector.replace(SLOTTED_PAREN, (m, paren) => ` > ${paren}`);
-      }
-    }
-    selector = selector.replace(DIR_PAREN, (m, before, dir) =>
-      `[dir="${dir}"] ${before}, ${before}[dir="${dir}"]`);
-    return {value: selector, combinator, stop};
-  }
-
-  _transformSimpleSelector(selector, scope) {
-    let p$ = selector.split(PSEUDO_PREFIX);
-    p$[0] += scope;
-    return p$.join(PSEUDO_PREFIX);
-  }
-
-  // :host(...) -> scopeName...
-  _transformHostSelector(selector, hostScope) {
-    let m = selector.match(HOST_PAREN);
-    let paren = m && m[2].trim() || '';
-    if (paren) {
-      if (!paren[0].match(SIMPLE_SELECTOR_PREFIX)) {
-        // paren starts with a type selector
-        let typeSelector = paren.split(SIMPLE_SELECTOR_PREFIX)[0];
-        // if the type selector is our hostScope then avoid pre-pending it
-        if (typeSelector === hostScope) {
-          return paren;
-        // otherwise, this selector should not match in this scope so
-        // output a bogus selector.
-        } else {
-          return SELECTOR_NO_MATCH;
-        }
-      } else {
-        // make sure to do a replace here to catch selectors like:
-        // `:host(.foo)::before`
-        return selector.replace(HOST_PAREN, function(m, host, paren) {
-          return hostScope + paren;
-        });
-      }
-    // if no paren, do a straight :host replacement.
-    // TODO(sorvell): this should not strictly be necessary but
-    // it's needed to maintain support for `:host[foo]` type selectors
-    // which have been improperly used under Shady DOM. This should be
-    // deprecated.
-    } else {
-      return selector.replace(HOST, hostScope);
-    }
-  }
-
-  /**
-   * @param {StyleNode} rule
-   */
-  documentRule(rule) {
-    // reset selector in case this is redone.
-    rule['selector'] = rule['parsedSelector'];
-    this.normalizeRootSelector(rule);
-    this._transformRule(rule, this._transformDocumentSelector);
-  }
-
-  /**
-   * @param {StyleNode} rule
-   */
-  normalizeRootSelector(rule) {
-    if (rule['selector'] === ROOT) {
-      rule['selector'] = 'html';
-    }
-  }
-
-/**
- * @param {string} selector
- */
-  _transformDocumentSelector(selector) {
-    return selector.match(SLOTTED) ?
-      this._transformComplexSelector(selector, SCOPE_DOC_SELECTOR) :
-      this._transformSimpleSelector(selector.trim(), SCOPE_DOC_SELECTOR);
-  }
-}
-
-let NTH = /:(nth[-\w]+)\(([^)]+)\)/;
-let SCOPE_DOC_SELECTOR = `:not(.${SCOPE_NAME})`;
-let COMPLEX_SELECTOR_SEP = ',';
-let SIMPLE_SELECTOR_SEP = /(^|[\s>+~]+)((?:\[.+?\]|[^\s>+~=\[])+)/g;
-let SIMPLE_SELECTOR_PREFIX = /[[.:#*]/;
-let HOST = ':host';
-let ROOT = ':root';
-let SLOTTED = '::slotted';
-let SLOTTED_START = new RegExp(`^(${SLOTTED})`);
-// NOTE: this supports 1 nested () pair for things like
-// :host(:not([selected]), more general support requires
-// parsing which seems like overkill
-let HOST_PAREN = /(:host)(?:\(((?:\([^)(]*\)|[^)(]*)+?)\))/;
-// similar to HOST_PAREN
-let SLOTTED_PAREN = /(?:::slotted)(?:\(((?:\([^)(]*\)|[^)(]*)+?)\))/;
-let DIR_PAREN = /(.*):dir\((?:(ltr|rtl))\)/;
-let CSS_CLASS_PREFIX = '.';
-let PSEUDO_PREFIX = ':';
-let CLASS = 'class';
-let SELECTOR_NO_MATCH = 'should_not_match';
-
-var StyleTransformer$1 = new StyleTransformer();
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/** @const {string} */
-const infoKey = '__styleInfo';
-
-class StyleInfo {
-  /**
-   * @param {Element} node
-   * @return {StyleInfo}
-   */
-  static get(node) {
-    if (node) {
-      return node[infoKey];
-    } else {
-      return null;
-    }
-  }
-  /**
-   * @param {!Element} node
-   * @param {StyleInfo} styleInfo
-   * @return {StyleInfo}
-   */
-  static set(node, styleInfo) {
-    node[infoKey] = styleInfo;
-    return styleInfo;
-  }
-  /**
-   * @param {StyleNode} ast
-   * @param {Node=} placeholder
-   * @param {Array<string>=} ownStylePropertyNames
-   * @param {string=} elementName
-   * @param {string=} typeExtension
-   * @param {string=} cssBuild
-   */
-  constructor(ast, placeholder, ownStylePropertyNames, elementName, typeExtension, cssBuild) {
-    /** @type {StyleNode} */
-    this.styleRules = ast || null;
-    /** @type {Node} */
-    this.placeholder = placeholder || null;
-    /** @type {!Array<string>} */
-    this.ownStylePropertyNames = ownStylePropertyNames || [];
-    /** @type {Array<Object>} */
-    this.overrideStyleProperties = null;
-    /** @type {string} */
-    this.elementName = elementName || '';
-    /** @type {string} */
-    this.cssBuild = cssBuild || '';
-    /** @type {string} */
-    this.typeExtension = typeExtension || '';
-    /** @type {Object<string, string>} */
-    this.styleProperties = null;
-    /** @type {?string} */
-    this.scopeSelector = null;
-    /** @type {HTMLStyleElement} */
-    this.customStyle = null;
-  }
-  _getStyleRules() {
-    return this.styleRules;
-  }
-}
-
-StyleInfo.prototype['_getStyleRules'] = StyleInfo.prototype._getStyleRules;
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-// TODO: dedupe with shady
-/**
- * @const {function(string):boolean}
- */
-const matchesSelector$1 = ((p) => p.matches || p.matchesSelector ||
-  p.mozMatchesSelector || p.msMatchesSelector ||
-p.oMatchesSelector || p.webkitMatchesSelector)(window.Element.prototype);
-
-const IS_IE = navigator.userAgent.match('Trident');
-
-const XSCOPE_NAME = 'x-scope';
-
-class StyleProperties {
-  get XSCOPE_NAME() {
-    return XSCOPE_NAME;
-  }
-/**
- * decorates styles with rule info and returns an array of used style property names
- *
- * @param {StyleNode} rules
- * @return {Array<string>}
- */
-  decorateStyles(rules) {
-    let self = this, props = {}, keyframes = [], ruleIndex = 0;
-    forEachRule(rules, function(rule) {
-      self.decorateRule(rule);
-      // mark in-order position of ast rule in styles block, used for cache key
-      rule.index = ruleIndex++;
-      self.collectPropertiesInCssText(rule.propertyInfo.cssText, props);
-    }, function onKeyframesRule(rule) {
-      keyframes.push(rule);
-    });
-    // Cache all found keyframes rules for later reference:
-    rules._keyframes = keyframes;
-    // return this list of property names *consumes* in these styles.
-    let names = [];
-    for (let i in props) {
-      names.push(i);
-    }
-    return names;
-  }
-
-  // decorate a single rule with property info
-  decorateRule(rule) {
-    if (rule.propertyInfo) {
-      return rule.propertyInfo;
-    }
-    let info = {}, properties = {};
-    let hasProperties = this.collectProperties(rule, properties);
-    if (hasProperties) {
-      info.properties = properties;
-      // TODO(sorvell): workaround parser seeing mixins as additional rules
-      rule['rules'] = null;
-    }
-    info.cssText = this.collectCssText(rule);
-    rule.propertyInfo = info;
-    return info;
-  }
-
-  // collects the custom properties from a rule's cssText
-  collectProperties(rule, properties) {
-    let info = rule.propertyInfo;
-    if (info) {
-      if (info.properties) {
-        Object.assign(properties, info.properties);
-        return true;
-      }
-    } else {
-      let m, rx = VAR_ASSIGN;
-      let cssText = rule['parsedCssText'];
-      let value;
-      let any;
-      while ((m = rx.exec(cssText))) {
-        // note: group 2 is var, 3 is mixin
-        value = (m[2] || m[3]).trim();
-        // value of 'inherit' or 'unset' is equivalent to not setting the property here
-        if (value !== 'inherit' || value !== 'unset') {
-          properties[m[1].trim()] = value;
-        }
-        any = true;
-      }
-      return any;
-    }
-
-  }
-
-  // returns cssText of properties that consume variables/mixins
-  collectCssText(rule) {
-    return this.collectConsumingCssText(rule['parsedCssText']);
-  }
-
-  // NOTE: we support consumption inside mixin assignment
-  // but not production, so strip out {...}
-  collectConsumingCssText(cssText) {
-    return cssText.replace(BRACKETED, '')
-      .replace(VAR_ASSIGN, '');
-  }
-
-  collectPropertiesInCssText(cssText, props) {
-    let m;
-    while ((m = VAR_CONSUMED.exec(cssText))) {
-      let name = m[1];
-      // This regex catches all variable names, and following non-whitespace char
-      // If next char is not ':', then variable is a consumer
-      if (m[2] !== ':') {
-        props[name] = true;
-      }
-    }
-  }
-
-  // turns custom properties into realized values.
-  reify(props) {
-    // big perf optimization here: reify only *own* properties
-    // since this object has __proto__ of the element's scope properties
-    let names = Object.getOwnPropertyNames(props);
-    for (let i=0, n; i < names.length; i++) {
-      n = names[i];
-      props[n] = this.valueForProperty(props[n], props);
-    }
-  }
-
-  // given a property value, returns the reified value
-  // a property value may be:
-  // (1) a literal value like: red or 5px;
-  // (2) a variable value like: var(--a), var(--a, red), or var(--a, --b) or
-  // var(--a, var(--b));
-  // (3) a literal mixin value like { properties }. Each of these properties
-  // can have values that are: (a) literal, (b) variables, (c) @apply mixins.
-  valueForProperty(property, props) {
-    // case (1) default
-    // case (3) defines a mixin and we have to reify the internals
-    if (property) {
-      if (property.indexOf(';') >=0) {
-        property = this.valueForProperties(property, props);
-      } else {
-        // case (2) variable
-        let self = this;
-        let fn = function(prefix, value, fallback, suffix) {
-          if (!value) {
-            return prefix + suffix;
-          }
-          let propertyValue = self.valueForProperty(props[value], props);
-          // if value is "initial", then the variable should be treated as unset
-          if (!propertyValue || propertyValue === 'initial') {
-            // fallback may be --a or var(--a) or literal
-            propertyValue = self.valueForProperty(props[fallback] || fallback, props) ||
-            fallback;
-          } else if (propertyValue === 'apply-shim-inherit') {
-            // CSS build will replace `inherit` with `apply-shim-inherit`
-            // for use with native css variables.
-            // Since we have full control, we can use `inherit` directly.
-            propertyValue = 'inherit';
-          }
-          return prefix + (propertyValue || '') + suffix;
-        };
-        property = processVariableAndFallback(property, fn);
-      }
-    }
-    return property && property.trim() || '';
-  }
-
-  // note: we do not yet support mixin within mixin
-  valueForProperties(property, props) {
-    let parts = property.split(';');
-    for (let i=0, p, m; i<parts.length; i++) {
-      if ((p = parts[i])) {
-        MIXIN_MATCH.lastIndex = 0;
-        m = MIXIN_MATCH.exec(p);
-        if (m) {
-          p = this.valueForProperty(props[m[1]], props);
-        } else {
-          let colon = p.indexOf(':');
-          if (colon !== -1) {
-            let pp = p.substring(colon);
-            pp = pp.trim();
-            pp = this.valueForProperty(pp, props) || pp;
-            p = p.substring(0, colon) + pp;
-          }
-        }
-        parts[i] = (p && p.lastIndexOf(';') === p.length - 1) ?
-          // strip trailing ;
-          p.slice(0, -1) :
-          p || '';
-      }
-    }
-    return parts.join(';');
-  }
-
-  applyProperties(rule, props) {
-    let output = '';
-    // dynamically added sheets may not be decorated so ensure they are.
-    if (!rule.propertyInfo) {
-      this.decorateRule(rule);
-    }
-    if (rule.propertyInfo.cssText) {
-      output = this.valueForProperties(rule.propertyInfo.cssText, props);
-    }
-    rule['cssText'] = output;
-  }
-
-  // Apply keyframe transformations to the cssText of a given rule. The
-  // keyframeTransforms object is a map of keyframe names to transformer
-  // functions which take in cssText and spit out transformed cssText.
-  applyKeyframeTransforms(rule, keyframeTransforms) {
-    let input = rule['cssText'];
-    let output = rule['cssText'];
-    if (rule.hasAnimations == null) {
-      // Cache whether or not the rule has any animations to begin with:
-      rule.hasAnimations = ANIMATION_MATCH.test(input);
-    }
-    // If there are no animations referenced, we can skip transforms:
-    if (rule.hasAnimations) {
-      let transform;
-      // If we haven't transformed this rule before, we iterate over all
-      // transforms:
-      if (rule.keyframeNamesToTransform == null) {
-        rule.keyframeNamesToTransform = [];
-        for (let keyframe in keyframeTransforms) {
-          transform = keyframeTransforms[keyframe];
-          output = transform(input);
-          // If the transform actually changed the CSS text, we cache the
-          // transform name for future use:
-          if (input !== output) {
-            input = output;
-            rule.keyframeNamesToTransform.push(keyframe);
-          }
-        }
-      } else {
-        // If we already have a list of keyframe names that apply to this
-        // rule, we apply only those keyframe name transforms:
-        for (let i = 0; i < rule.keyframeNamesToTransform.length; ++i) {
-          transform = keyframeTransforms[rule.keyframeNamesToTransform[i]];
-          input = transform(input);
-        }
-        output = input;
-      }
-    }
-    rule['cssText'] = output;
-  }
-
-  // Test if the rules in these styles matches the given `element` and if so,
-  // collect any custom properties into `props`.
-  /**
-   * @param {StyleNode} rules
-   * @param {Element} element
-   */
-  propertyDataFromStyles(rules, element) {
-    let props = {}, self = this;
-    // generates a unique key for these matches
-    let o = [];
-    // note: active rules excludes non-matching @media rules
-    forEachRule(rules, function(rule) {
-      // TODO(sorvell): we could trim the set of rules at declaration
-      // time to only include ones that have properties
-      if (!rule.propertyInfo) {
-        self.decorateRule(rule);
-      }
-      // match element against transformedSelector: selector may contain
-      // unwanted uniquification and parsedSelector does not directly match
-      // for :host selectors.
-      let selectorToMatch = rule.transformedSelector || rule['parsedSelector'];
-      if (element && rule.propertyInfo.properties && selectorToMatch) {
-        if (matchesSelector$1.call(element, selectorToMatch)) {
-          self.collectProperties(rule, props);
-          // produce numeric key for these matches for lookup
-          addToBitMask(rule.index, o);
-        }
-      }
-    }, null, true);
-    return {properties: props, key: o};
-  }
-
-  /**
-   * @param {Element} scope
-   * @param {StyleNode} rule
-   * @param {string|undefined} cssBuild
-   * @param {function(Object)} callback
-   */
-  whenHostOrRootRule(scope, rule, cssBuild, callback) {
-    if (!rule.propertyInfo) {
-      this.decorateRule(rule);
-    }
-    if (!rule.propertyInfo.properties) {
-      return;
-    }
-    let {is, typeExtension} = getIsExtends(scope);
-    let hostScope = is ?
-      StyleTransformer$1._calcHostScope(is, typeExtension) :
-      'html';
-    let parsedSelector = rule['parsedSelector'];
-    let isRoot = (parsedSelector === ':host > *' || parsedSelector === 'html');
-    let isHost = parsedSelector.indexOf(':host') === 0 && !isRoot;
-    // build info is either in scope (when scope is an element) or in the style
-    // when scope is the default scope; note: this allows default scope to have
-    // mixed mode built and unbuilt styles.
-    if (cssBuild === 'shady') {
-      // :root -> x-foo > *.x-foo for elements and html for custom-style
-      isRoot = parsedSelector === (hostScope + ' > *.' + hostScope) || parsedSelector.indexOf('html') !== -1;
-      // :host -> x-foo for elements, but sub-rules have .x-foo in them
-      isHost = !isRoot && parsedSelector.indexOf(hostScope) === 0;
-    }
-    if (cssBuild === 'shadow') {
-      isRoot = parsedSelector === ':host > *' || parsedSelector === 'html';
-      isHost = isHost && !isRoot;
-    }
-    if (!isRoot && !isHost) {
-      return;
-    }
-    let selectorToMatch = hostScope;
-    if (isHost) {
-      // need to transform :host under ShadowDOM because `:host` does not work with `matches`
-      if (nativeShadow && !rule.transformedSelector) {
-        // transform :host into a matchable selector
-        rule.transformedSelector =
-        StyleTransformer$1._transformRuleCss(
-          rule,
-          StyleTransformer$1._transformComplexSelector,
-          StyleTransformer$1._calcElementScope(is),
-          hostScope
-        );
-      }
-      selectorToMatch = rule.transformedSelector || hostScope;
-    }
-    callback({
-      selector: selectorToMatch,
-      isHost: isHost,
-      isRoot: isRoot
-    });
-  }
-/**
- * @param {Element} scope
- * @param {StyleNode} rules
- * @return {Object}
- */
-  hostAndRootPropertiesForScope(scope, rules) {
-    let hostProps = {}, rootProps = {}, self = this;
-    // note: active rules excludes non-matching @media rules
-    let cssBuild = rules && rules['__cssBuild'];
-    forEachRule(rules, function(rule) {
-      // if scope is StyleDefaults, use _element for matchesSelector
-      self.whenHostOrRootRule(scope, rule, cssBuild, function(info) {
-        let element = scope._element || scope;
-        if (matchesSelector$1.call(element, info.selector)) {
-          if (info.isHost) {
-            self.collectProperties(rule, hostProps);
-          } else {
-            self.collectProperties(rule, rootProps);
-          }
-        }
-      });
-    }, null, true);
-    return {rootProps: rootProps, hostProps: hostProps};
-  }
-
-  /**
-   * @param {Element} element
-   * @param {Object} properties
-   * @param {string} scopeSelector
-   */
-  transformStyles(element, properties, scopeSelector) {
-    let self = this;
-    let {is, typeExtension} = getIsExtends(element);
-    let hostSelector = StyleTransformer$1
-      ._calcHostScope(is, typeExtension);
-    let rxHostSelector = element.extends ?
-      '\\' + hostSelector.slice(0, -1) + '\\]' :
-      hostSelector;
-    let hostRx = new RegExp(HOST_PREFIX + rxHostSelector +
-      HOST_SUFFIX);
-    let rules = StyleInfo.get(element).styleRules;
-    let keyframeTransforms =
-      this._elementKeyframeTransforms(element, rules, scopeSelector);
-    return StyleTransformer$1.elementStyles(element, rules, function(rule) {
-      self.applyProperties(rule, properties);
-      if (!nativeShadow &&
-          !isKeyframesSelector(rule) &&
-          rule['cssText']) {
-        // NOTE: keyframe transforms only scope munge animation names, so it
-        // is not necessary to apply them in ShadowDOM.
-        self.applyKeyframeTransforms(rule, keyframeTransforms);
-        self._scopeSelector(rule, hostRx, hostSelector, scopeSelector);
-      }
-    });
-  }
-
-  /**
-   * @param {Element} element
-   * @param {StyleNode} rules
-   * @param {string} scopeSelector
-   * @return {Object}
-   */
-  _elementKeyframeTransforms(element, rules, scopeSelector) {
-    let keyframesRules = rules._keyframes;
-    let keyframeTransforms = {};
-    if (!nativeShadow && keyframesRules) {
-      // For non-ShadowDOM, we transform all known keyframes rules in
-      // advance for the current scope. This allows us to catch keyframes
-      // rules that appear anywhere in the stylesheet:
-      for (let i = 0, keyframesRule = keyframesRules[i];
-           i < keyframesRules.length;
-           keyframesRule = keyframesRules[++i]) {
-        this._scopeKeyframes(keyframesRule, scopeSelector);
-        keyframeTransforms[keyframesRule['keyframesName']] =
-            this._keyframesRuleTransformer(keyframesRule);
-      }
-    }
-    return keyframeTransforms;
-  }
-
-  // Generate a factory for transforming a chunk of CSS text to handle a
-  // particular scoped keyframes rule.
-  /**
-   * @param {StyleNode} keyframesRule
-   * @return {function(string):string}
-   */
-  _keyframesRuleTransformer(keyframesRule) {
-    return function(cssText) {
-      return cssText.replace(
-          keyframesRule.keyframesNameRx,
-          keyframesRule.transformedKeyframesName);
-    };
-  }
-
-/**
- * Transforms `@keyframes` names to be unique for the current host.
- * Example: @keyframes foo-anim -> @keyframes foo-anim-x-foo-0
- *
- * @param {StyleNode} rule
- * @param {string} scopeId
- */
-  _scopeKeyframes(rule, scopeId) {
-    rule.keyframesNameRx = new RegExp(rule['keyframesName'], 'g');
-    rule.transformedKeyframesName = rule['keyframesName'] + '-' + scopeId;
-    rule.transformedSelector = rule.transformedSelector || rule['selector'];
-    rule['selector'] = rule.transformedSelector.replace(
-        rule['keyframesName'], rule.transformedKeyframesName);
-  }
-
-  // Strategy: x scope shim a selector e.g. to scope `.x-foo-42` (via classes):
-  // non-host selector: .a.x-foo -> .x-foo-42 .a.x-foo
-  // host selector: x-foo.wide -> .x-foo-42.wide
-  // note: we use only the scope class (.x-foo-42) and not the hostSelector
-  // (x-foo) to scope :host rules; this helps make property host rules
-  // have low specificity. They are overrideable by class selectors but,
-  // unfortunately, not by type selectors (e.g. overriding via
-  // `.special` is ok, but not by `x-foo`).
-  /**
-   * @param {StyleNode} rule
-   * @param {RegExp} hostRx
-   * @param {string} hostSelector
-   * @param {string} scopeId
-   */
-  _scopeSelector(rule, hostRx, hostSelector, scopeId) {
-    rule.transformedSelector = rule.transformedSelector || rule['selector'];
-    let selector = rule.transformedSelector;
-    let scope = '.' + scopeId;
-    let parts = selector.split(',');
-    for (let i=0, l=parts.length, p; (i<l) && (p=parts[i]); i++) {
-      parts[i] = p.match(hostRx) ?
-        p.replace(hostSelector, scope) :
-        scope + ' ' + p;
-    }
-    rule['selector'] = parts.join(',');
-  }
-
-  /**
-   * @param {Element} element
-   * @param {string} selector
-   * @param {string} old
-   */
-  applyElementScopeSelector(element, selector, old) {
-    let c = element.getAttribute('class') || '';
-    let v = c;
-    if (old) {
-      v = c.replace(
-        new RegExp('\\s*' + XSCOPE_NAME + '\\s*' + old + '\\s*', 'g'), ' ');
-    }
-    v += (v ? ' ' : '') + XSCOPE_NAME + ' ' + selector;
-    if (c !== v) {
-      setElementClassRaw(element, v);
-    }
-  }
-
-  /**
-   * @param {HTMLElement} element
-   * @param {Object} properties
-   * @param {string} selector
-   * @param {HTMLStyleElement} style
-   * @return {HTMLStyleElement}
-   */
-  applyElementStyle(element, properties, selector, style) {
-    // calculate cssText to apply
-    let cssText = style ? style.textContent || '' :
-      this.transformStyles(element, properties, selector);
-    // if shady and we have a cached style that is not style, decrement
-    let styleInfo = StyleInfo.get(element);
-    let s = styleInfo.customStyle;
-    if (s && !nativeShadow && (s !== style)) {
-      s['_useCount']--;
-      if (s['_useCount'] <= 0 && s.parentNode) {
-        s.parentNode.removeChild(s);
-      }
-    }
-    // apply styling always under native or if we generated style
-    // or the cached style is not in document(!)
-    if (nativeShadow) {
-      // update existing style only under native
-      if (styleInfo.customStyle) {
-        styleInfo.customStyle.textContent = cssText;
-        style = styleInfo.customStyle;
-      // otherwise, if we have css to apply, do so
-      } else if (cssText) {
-        // apply css after the scope style of the element to help with
-        // style precedence rules.
-        style = applyCss(cssText, selector, element.shadowRoot,
-          styleInfo.placeholder);
-      }
-    } else {
-      // shady and no cache hit
-      if (!style) {
-        // apply css after the scope style of the element to help with
-        // style precedence rules.
-        if (cssText) {
-          style = applyCss(cssText, selector, null,
-            styleInfo.placeholder);
-        }
-      // shady and cache hit but not in document
-      } else if (!style.parentNode) {
-        applyStyle(style, null, styleInfo.placeholder);
-      }
-
-    }
-    // ensure this style is our custom style and increment its use count.
-    if (style) {
-      style['_useCount'] = style['_useCount'] || 0;
-      // increment use count if we changed styles
-      if (styleInfo.customStyle != style) {
-        style['_useCount']++;
-      }
-      styleInfo.customStyle = style;
-    }
-    // @media rules may be stale in IE 10 and 11
-    if (IS_IE) {
-      style.textContent = style.textContent;
-    }
-    return style;
-  }
-
-  /**
-   * @param {Element} style
-   * @param {Object} properties
-   */
-  applyCustomStyle(style, properties) {
-    let rules = rulesForStyle(/** @type {HTMLStyleElement} */(style));
-    let self = this;
-    style.textContent = toCssText(rules, function(/** StyleNode */rule) {
-      let css = rule['cssText'] = rule['parsedCssText'];
-      if (rule.propertyInfo && rule.propertyInfo.cssText) {
-        // remove property assignments
-        // so next function isn't confused
-        // NOTE: we have 3 categories of css:
-        // (1) normal properties,
-        // (2) custom property assignments (--foo: red;),
-        // (3) custom property usage: border: var(--foo); @apply(--foo);
-        // In elements, 1 and 3 are separated for efficiency; here they
-        // are not and this makes this case unique.
-        css = removeCustomPropAssignment(/** @type {string} */(css));
-        // replace with reified properties, scenario is same as mixin
-        rule['cssText'] = self.valueForProperties(css, properties);
-      }
-    });
-  }
-}
-
-/**
- * @param {number} n
- * @param {Array<number>} bits
- */
-function addToBitMask(n, bits) {
-  let o = parseInt(n / 32, 10);
-  let v = 1 << (n % 32);
-  bits[o] = (bits[o] || 0) | v;
-}
-
-var StyleProperties$1 = new StyleProperties();
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/** @type {Object<string, !Node>} */
-let placeholderMap = {};
-
-/**
- * @const {CustomElementRegistry}
- */
-const ce = window['customElements'];
-if (ce && !nativeShadow) {
-  /**
-   * @const {function(this:CustomElementRegistry, string,function(new:HTMLElement),{extends: string}=)}
-   */
-  const origDefine = ce['define'];
-  /**
-   * @param {string} name
-   * @param {function(new:HTMLElement)} clazz
-   * @param {{extends: string}=} options
-   * @return {function(new:HTMLElement)}
-   */
-  const wrappedDefine = (name, clazz, options) => {
-    placeholderMap[name] = applyStylePlaceHolder(name);
-    return origDefine.call(/** @type {!CustomElementRegistry} */(ce), name, clazz, options);
-  };
-  ce['define'] = wrappedDefine;
-}
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-class StyleCache {
-  constructor(typeMax = 100) {
-    // map element name -> [{properties, styleElement, scopeSelector}]
-    this.cache = {};
-    this.typeMax = typeMax;
-  }
-
-  _validate(cacheEntry, properties, ownPropertyNames) {
-    for (let idx = 0; idx < ownPropertyNames.length; idx++) {
-      let pn = ownPropertyNames[idx];
-      if (cacheEntry.properties[pn] !== properties[pn]) {
-        return false;
-      }
-    }
-    return true;
-  }
-
-  store(tagname, properties, styleElement, scopeSelector) {
-    let list = this.cache[tagname] || [];
-    list.push({properties, styleElement, scopeSelector});
-    if (list.length > this.typeMax) {
-      list.shift();
-    }
-    this.cache[tagname] = list;
-  }
-
-  fetch(tagname, properties, ownPropertyNames) {
-    let list = this.cache[tagname];
-    if (!list) {
-      return;
-    }
-    // reverse list for most-recent lookups
-    for (let idx = list.length - 1; idx >= 0; idx--) {
-      let entry = list[idx];
-      if (this._validate(entry, properties, ownPropertyNames)) {
-        return entry;
-      }
-    }
-  }
-}
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-let flush$1 = function() {};
-
-if (!nativeShadow) {
-  let elementNeedsScoping = (element) => {
-    return (element.classList &&
-      !element.classList.contains(StyleTransformer$1.SCOPE_NAME) ||
-      // note: necessary for IE11
-      (element instanceof window['SVGElement'] && (!element.hasAttribute('class') ||
-      element.getAttribute('class').indexOf(StyleTransformer$1.SCOPE_NAME) < 0)));
-  };
-
-/**
- * @param {Array<MutationRecord|null>|null} mxns
- */
-  let handler = (mxns) => {
-    for (let x=0; x < mxns.length; x++) {
-      let mxn = mxns[x];
-      if (mxn.target === document.documentElement ||
-        mxn.target === document.head) {
-        continue;
-      }
-      for (let i=0; i < mxn.addedNodes.length; i++) {
-        let n = mxn.addedNodes[i];
-        if (elementNeedsScoping(n)) {
-          let root = n.getRootNode();
-          if (root.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
-            // may no longer be in a shadowroot
-            let host = /** @type {ShadowRoot} */(root).host;
-            if (host) {
-              let {is: scope} = getIsExtends(host);
-              StyleTransformer$1.dom(n, scope);
-            }
-          }
-        }
-      }
-      for (let i=0; i < mxn.removedNodes.length; i++) {
-        let n = /** @type {HTMLElement} */(mxn.removedNodes[i]);
-        if (n.nodeType === Node.ELEMENT_NODE) {
-          let classes = undefined;
-          if (n.classList) {
-            classes = Array.from(n.classList);
-          } else if (n.hasAttribute('class')) {
-            classes = n.getAttribute('class').split(/\s+/);
-          }
-          if (classes !== undefined) {
-            // NOTE: relies on the scoping class always being adjacent to the
-            // SCOPE_NAME class.
-            let classIdx = classes.indexOf(StyleTransformer$1.SCOPE_NAME);
-            if (classIdx >= 0) {
-              let scope = classes[classIdx + 1];
-              if (scope) {
-                StyleTransformer$1.dom(n, scope, true);
-              }
-            }
-          }
-        }
-      }
-    }
-  };
-
-  let observer = new MutationObserver(handler);
-  let start = (node) => {
-    observer.observe(node, {childList: true, subtree: true});
-  };
-  let nativeCustomElements = (window.customElements &&
-    !window['customElements']['flush']);
-  // need to start immediately with native custom elements
-  // TODO(dfreedm): with polyfilled HTMLImports and native custom elements
-  // excessive mutations may be observed; this can be optimized via cooperation
-  // with the HTMLImports polyfill.
-  if (nativeCustomElements) {
-    start(document);
-  } else {
-    let delayedStart = () => {
-      start(document.body);
-    };
-    // use polyfill timing if it's available
-    if (window['HTMLImports']) {
-      window['HTMLImports']['whenReady'](delayedStart);
-    // otherwise push beyond native imports being ready
-    // which requires RAF + readystate interactive.
-    } else {
-      requestAnimationFrame(function() {
-        if (document.readyState === 'loading') {
-          let listener = function() {
-            delayedStart();
-            document.removeEventListener('readystatechange', listener);
-          };
-          document.addEventListener('readystatechange', listener);
-        } else {
-          delayedStart();
-        }
-      });
-    }
-  }
-
-  flush$1 = function() {
-    handler(observer.takeRecords());
-  };
-}
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/**
- * @const {!Object<string, !HTMLTemplateElement>}
- */
-const templateMap = {};
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/**
- * @const {Promise<void>}
- */
-const promise = Promise.resolve();
-
-/**
- * @param {string} elementName
- */
-function invalidate(elementName){
-  let template = templateMap[elementName];
-  if (template) {
-    invalidateTemplate(template);
-  }
-}
-
-/**
- * @param {HTMLTemplateElement} template
- */
-function invalidateTemplate(template) {
-  template['_applyShimInvalid'] = true;
-}
-
-/**
- * @param {string} elementName
- * @return {boolean}
- */
-
-
-/**
- * @param {HTMLTemplateElement} template
- * @return {boolean}
- */
-function templateIsValid(template) {
-  return !template['_applyShimInvalid'];
-}
-
-/**
- * @param {string} elementName
- * @return {boolean}
- */
-
-
-/**
- * @param {HTMLTemplateElement} template
- * @return {boolean}
- */
-function templateIsValidating(template) {
-  return template._validating;
-}
-
-/**
- * the template is marked as `validating` for one microtask so that all instances
- * found in the tree crawl of `applyStyle` will update themselves,
- * but the template will only be updated once.
- * @param {string} elementName
-*/
-
-
-/**
- * @param {HTMLTemplateElement} template
- */
-function startValidatingTemplate(template) {
-  if (!template._validating) {
-    template._validating = true;
-    promise.then(function() {
-      template['_applyShimInvalid'] = false;
-      template._validating = false;
-    });
-  }
-}
-
-/**
- * @return {boolean}
- */
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/** @type {Promise<void>} */
-let readyPromise = null;
-
-/** @type {?function(?function())} */
-let whenReady = window['HTMLImports'] && window['HTMLImports']['whenReady'] || null;
-
-/** @type {function()} */
-let resolveFn;
-
-/**
- * @param {?function()} callback
- */
-function documentWait(callback) {
-  if (whenReady) {
-    whenReady(callback);
-  } else {
-    if (!readyPromise) {
-      readyPromise = new Promise((resolve) => {resolveFn = resolve;});
-      if (document.readyState === 'complete') {
-        resolveFn();
-      } else {
-        document.addEventListener('readystatechange', () => {
-          if (document.readyState === 'complete') {
-            resolveFn();
-          }
-        });
-      }
-    }
-    readyPromise.then(function(){ callback && callback(); });
-  }
-}
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/**
- * @param {Element} element
- * @param {Object=} properties
- */
-function updateNativeProperties(element, properties) {
-  // remove previous properties
-  for (let p in properties) {
-    // NOTE: for bc with shim, don't apply null values.
-    if (p === null) {
-      element.style.removeProperty(p);
-    } else {
-      element.style.setProperty(p, properties[p]);
-    }
-  }
-}
-
-/**
- * @param {Element} element
- * @param {string} property
- * @return {string}
- */
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/**
- * @typedef {HTMLStyleElement | {getStyle: function():HTMLStyleElement}}
- */
-
-
-const SEEN_MARKER = '__seenByShadyCSS';
-const CACHED_STYLE = '__shadyCSSCachedStyle';
-
-/** @type {?function(!HTMLStyleElement)} */
-let transformFn = null;
-
-/** @type {?function()} */
-let validateFn = null;
-
-/**
-This interface is provided to add document-level <style> elements to ShadyCSS for processing.
-These styles must be processed by ShadyCSS to simulate ShadowRoot upper-bound encapsulation from outside styles
-In addition, these styles may also need to be processed for @apply rules and CSS Custom Properties
-
-To add document-level styles to ShadyCSS, one can call `ShadyCSS.addDocumentStyle(styleElement)` or `ShadyCSS.addDocumentStyle({getStyle: () => styleElement})`
-
-In addition, if the process used to discover document-level styles can be synchronously flushed, one should set `ShadyCSS.documentStyleFlush`.
-This function will be called when calculating styles.
-
-An example usage of the document-level styling api can be found in `examples/document-style-lib.js`
-
-@unrestricted
-*/
-class CustomStyleInterface$1 {
-  constructor() {
-    /** @type {!Array<!CustomStyleProvider>} */
-    this['customStyles'] = [];
-    this['enqueued'] = false;
-  }
-  /**
-   * Queue a validation for new custom styles to batch style recalculations
-   */
-  enqueueDocumentValidation() {
-    if (this['enqueued'] || !validateFn) {
-      return;
-    }
-    this['enqueued'] = true;
-    documentWait(validateFn);
-  }
-  /**
-   * @param {!HTMLStyleElement} style
-   */
-  addCustomStyle(style) {
-    if (!style[SEEN_MARKER]) {
-      style[SEEN_MARKER] = true;
-      this['customStyles'].push(style);
-      this.enqueueDocumentValidation();
-    }
-  }
-  /**
-   * @param {!CustomStyleProvider} customStyle
-   * @return {HTMLStyleElement}
-   */
-  getStyleForCustomStyle(customStyle) {
-    if (customStyle[CACHED_STYLE]) {
-      return customStyle[CACHED_STYLE];
-    }
-    let style;
-    if (customStyle['getStyle']) {
-      style = customStyle['getStyle']();
-    } else {
-      style = customStyle;
-    }
-    return style;
-  }
-  /**
-   * @return {!Array<!CustomStyleProvider>}
-   */
-  processStyles() {
-    let cs = this['customStyles'];
-    for (let i = 0; i < cs.length; i++) {
-      let customStyle = cs[i];
-      if (customStyle[CACHED_STYLE]) {
-        continue;
-      }
-      let style = this.getStyleForCustomStyle(customStyle);
-      if (style) {
-        // HTMLImports polyfill may have cloned the style into the main document,
-        // which is referenced with __appliedElement.
-        // Also, we must copy over the attributes.
-        let appliedStyle = /** @type {HTMLStyleElement} */(style['__appliedElement']);
-        if (appliedStyle) {
-          for (let i = 0; i < style.attributes.length; i++) {
-            let attr = style.attributes[i];
-            appliedStyle.setAttribute(attr.name, attr.value);
-          }
-        }
-        let styleToTransform = appliedStyle || style;
-        if (transformFn) {
-          transformFn(styleToTransform);
-        }
-        customStyle[CACHED_STYLE] = styleToTransform;
-      }
-    }
-    return cs;
-  }
-}
-
-CustomStyleInterface$1.prototype['addCustomStyle'] = CustomStyleInterface$1.prototype.addCustomStyle;
-CustomStyleInterface$1.prototype['getStyleForCustomStyle'] = CustomStyleInterface$1.prototype.getStyleForCustomStyle;
-CustomStyleInterface$1.prototype['processStyles'] = CustomStyleInterface$1.prototype.processStyles;
-
-Object.defineProperties(CustomStyleInterface$1.prototype, {
-  'transformCallback': {
-    /** @return {?function(!HTMLStyleElement)} */
-    get() {
-      return transformFn;
-    },
-    /** @param {?function(!HTMLStyleElement)} fn */
-    set(fn) {
-      transformFn = fn;
-    }
-  },
-  'validateCallback': {
-    /** @return {?function()} */
-    get() {
-      return validateFn;
-    },
-    /**
-     * @param {?function()} fn
-     * @this {CustomStyleInterface}
-     */
-    set(fn) {
-      let needsEnqueue = false;
-      if (!validateFn) {
-        needsEnqueue = true;
-      }
-      validateFn = fn;
-      if (needsEnqueue) {
-        this.enqueueDocumentValidation();
-      }
-    },
-  }
-});
-
-/** @typedef {{
- * customStyles: !Array<!CustomStyleProvider>,
- * addCustomStyle: function(!CustomStyleProvider),
- * getStyleForCustomStyle: function(!CustomStyleProvider): HTMLStyleElement,
- * findStyles: function(),
- * transformCallback: ?function(!HTMLStyleElement),
- * validateCallback: ?function()
- * }}
- */
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/**
- * @const {StyleCache}
- */
-const styleCache = new StyleCache();
-
-class ScopingShim {
-  constructor() {
-    this._scopeCounter = {};
-    this._documentOwner = document.documentElement;
-    let ast = new StyleNode();
-    ast['rules'] = [];
-    this._documentOwnerStyleInfo = StyleInfo.set(this._documentOwner, new StyleInfo(ast));
-    this._elementsHaveApplied = false;
-    this._applyShim = null;
-    /** @type {?CustomStyleInterfaceInterface} */
-    this._customStyleInterface = null;
-    documentWait(() => {
-      this._ensure();
-    });
-  }
-  flush() {
-    flush$1();
-  }
-  _generateScopeSelector(name) {
-    let id = this._scopeCounter[name] = (this._scopeCounter[name] || 0) + 1;
-    return `${name}-${id}`;
-  }
-  getStyleAst(style) {
-    return rulesForStyle(style);
-  }
-  styleAstToString(ast) {
-    return toCssText(ast);
-  }
-  _gatherStyles(template) {
-    let styles = template.content.querySelectorAll('style');
-    let cssText = [];
-    for (let i = 0; i < styles.length; i++) {
-      let s = styles[i];
-      cssText.push(s.textContent);
-      s.parentNode.removeChild(s);
-    }
-    return cssText.join('').trim();
-  }
-  _getCssBuild(template) {
-    let style = template.content.querySelector('style');
-    if (!style) {
-      return '';
-    }
-    return style.getAttribute('css-build') || '';
-  }
-  /**
-   * Prepare the styling and template for the given element type
-   *
-   * @param {HTMLTemplateElement} template
-   * @param {string} elementName
-   * @param {string=} typeExtension
-   */
-  prepareTemplate(template, elementName, typeExtension) {
-    if (template._prepared) {
-      return;
-    }
-    template._prepared = true;
-    template.name = elementName;
-    template.extends = typeExtension;
-    templateMap[elementName] = template;
-    let cssBuild = this._getCssBuild(template);
-    let cssText = this._gatherStyles(template);
-    let info = {
-      is: elementName,
-      extends: typeExtension,
-      __cssBuild: cssBuild,
-    };
-    if (!nativeShadow) {
-      StyleTransformer$1.dom(template.content, elementName);
-    }
-    // check if the styling has mixin definitions or uses
-    this._ensure();
-    let hasMixins = this._applyShim['detectMixin'](cssText);
-    let ast = parse(cssText);
-    // only run the applyshim transforms if there is a mixin involved
-    if (hasMixins && nativeCssVariables) {
-      this._applyShim['transformRules'](ast, elementName);
-    }
-    template['_styleAst'] = ast;
-    template._cssBuild = cssBuild;
-
-    let ownPropertyNames = [];
-    if (!nativeCssVariables) {
-      ownPropertyNames = StyleProperties$1.decorateStyles(template['_styleAst'], info);
-    }
-    if (!ownPropertyNames.length || nativeCssVariables) {
-      let root = nativeShadow ? template.content : null;
-      let placeholder = placeholderMap[elementName];
-      let style = this._generateStaticStyle(info, template['_styleAst'], root, placeholder);
-      template._style = style;
-    }
-    template._ownPropertyNames = ownPropertyNames;
-  }
-  _generateStaticStyle(info, rules, shadowroot, placeholder) {
-    let cssText = StyleTransformer$1.elementStyles(info, rules);
-    if (cssText.length) {
-      return applyCss(cssText, info.is, shadowroot, placeholder);
-    }
-  }
-  _prepareHost(host) {
-    let {is, typeExtension} = getIsExtends(host);
-    let placeholder = placeholderMap[is];
-    let template = templateMap[is];
-    let ast;
-    let ownStylePropertyNames;
-    let cssBuild;
-    if (template) {
-      ast = template['_styleAst'];
-      ownStylePropertyNames = template._ownPropertyNames;
-      cssBuild = template._cssBuild;
-    }
-    return StyleInfo.set(host,
-      new StyleInfo(
-        ast,
-        placeholder,
-        ownStylePropertyNames,
-        is,
-        typeExtension,
-        cssBuild
-      )
-    );
-  }
-  _ensureApplyShim() {
-    if (this._applyShim) {
-      return;
-    } else if (window.ShadyCSS.ApplyShim) {
-      this._applyShim = window.ShadyCSS.ApplyShim;
-      this._applyShim['invalidCallback'] = invalidate;
-    } else {
-      this._applyShim = {
-        /* eslint-disable no-unused-vars */
-        ['detectMixin'](str){return false},
-        ['transformRule'](ast){},
-        ['transformRules'](ast, name){},
-        /* eslint-enable no-unused-vars */
-      };
-    }
-  }
-  _ensureCustomStyleInterface() {
-    if (this._customStyleInterface) {
-      return;
-    } else if (window.ShadyCSS.CustomStyleInterface) {
-      this._customStyleInterface = /** @type {!CustomStyleInterfaceInterface} */(window.ShadyCSS.CustomStyleInterface);
-      /** @type {function(!HTMLStyleElement)} */
-      this._customStyleInterface['transformCallback'] = (style) => {this.transformCustomStyleForDocument(style);};
-      this._customStyleInterface['validateCallback'] = () => {
-        requestAnimationFrame(() => {
-          if (this._customStyleInterface['enqueued'] || this._elementsHaveApplied) {
-            this.flushCustomStyles();
-          }
-        });
-      };
-    } else {
-      this._customStyleInterface = /** @type {!CustomStyleInterfaceInterface} */({
-        ['processStyles']() {},
-        ['enqueued']: false,
-        ['getStyleForCustomStyle'](s) { return null } // eslint-disable-line no-unused-vars
-      });
-    }
-  }
-  _ensure() {
-    this._ensureApplyShim();
-    this._ensureCustomStyleInterface();
-  }
-  /**
-   * Flush and apply custom styles to document
-   */
-  flushCustomStyles() {
-    this._ensure();
-    let customStyles = this._customStyleInterface['processStyles']();
-    // early return if custom-styles don't need validation
-    if (!this._customStyleInterface['enqueued']) {
-      return;
-    }
-    if (!nativeCssVariables) {
-      this._updateProperties(this._documentOwner, this._documentOwnerStyleInfo);
-      this._applyCustomStyles(customStyles);
-    } else {
-      this._revalidateCustomStyleApplyShim(customStyles);
-    }
-    this._customStyleInterface['enqueued'] = false;
-    // if custom elements have upgraded and there are no native css variables, we must recalculate the whole tree
-    if (this._elementsHaveApplied && !nativeCssVariables) {
-      this.styleDocument();
-    }
-  }
-  /**
-   * Apply styles for the given element
-   *
-   * @param {!HTMLElement} host
-   * @param {Object=} overrideProps
-   */
-  styleElement(host, overrideProps) {
-    let {is} = getIsExtends(host);
-    let styleInfo = StyleInfo.get(host);
-    if (!styleInfo) {
-      styleInfo = this._prepareHost(host);
-    }
-    // Only trip the `elementsHaveApplied` flag if a node other that the root document has `applyStyle` called
-    if (!this._isRootOwner(host)) {
-      this._elementsHaveApplied = true;
-    }
-    if (overrideProps) {
-      styleInfo.overrideStyleProperties =
-        styleInfo.overrideStyleProperties || {};
-      Object.assign(styleInfo.overrideStyleProperties, overrideProps);
-    }
-    if (!nativeCssVariables) {
-     this._updateProperties(host, styleInfo);
-      if (styleInfo.ownStylePropertyNames && styleInfo.ownStylePropertyNames.length) {
-        this._applyStyleProperties(host, styleInfo);
-      }
-    } else {
-      if (styleInfo.overrideStyleProperties) {
-        updateNativeProperties(host, styleInfo.overrideStyleProperties);
-      }
-      let template = templateMap[is];
-      // bail early if there is no shadowroot for this element
-      if (!template && !this._isRootOwner(host)) {
-        return;
-      }
-      if (template && template._style && !templateIsValid(template)) {
-        // update template
-        if (!templateIsValidating(template)) {
-          this._ensure();
-          this._applyShim['transformRules'](template['_styleAst'], is);
-          template._style.textContent = StyleTransformer$1.elementStyles(host, styleInfo.styleRules);
-          startValidatingTemplate(template);
-        }
-        // update instance if native shadowdom
-        if (nativeShadow) {
-          let root = host.shadowRoot;
-          if (root) {
-            let style = root.querySelector('style');
-            style.textContent = StyleTransformer$1.elementStyles(host, styleInfo.styleRules);
-          }
-        }
-        styleInfo.styleRules = template['_styleAst'];
-      }
-    }
-  }
-  _styleOwnerForNode(node) {
-    let root = node.getRootNode();
-    let host = root.host;
-    if (host) {
-      if (StyleInfo.get(host)) {
-        return host;
-      } else {
-        return this._styleOwnerForNode(host);
-      }
-    }
-    return this._documentOwner;
-  }
-  _isRootOwner(node) {
-    return (node === this._documentOwner);
-  }
-  _applyStyleProperties(host, styleInfo) {
-    let is = getIsExtends(host).is;
-    let cacheEntry = styleCache.fetch(is, styleInfo.styleProperties, styleInfo.ownStylePropertyNames);
-    let cachedScopeSelector = cacheEntry && cacheEntry.scopeSelector;
-    let cachedStyle = cacheEntry ? cacheEntry.styleElement : null;
-    let oldScopeSelector = styleInfo.scopeSelector;
-    // only generate new scope if cached style is not found
-    styleInfo.scopeSelector = cachedScopeSelector || this._generateScopeSelector(is);
-    let style = StyleProperties$1.applyElementStyle(host, styleInfo.styleProperties, styleInfo.scopeSelector, cachedStyle);
-    if (!nativeShadow) {
-      StyleProperties$1.applyElementScopeSelector(host, styleInfo.scopeSelector, oldScopeSelector);
-    }
-    if (!cacheEntry) {
-      styleCache.store(is, styleInfo.styleProperties, style, styleInfo.scopeSelector);
-    }
-    return style;
-  }
-  _updateProperties(host, styleInfo) {
-    let owner = this._styleOwnerForNode(host);
-    let ownerStyleInfo = StyleInfo.get(owner);
-    let ownerProperties = ownerStyleInfo.styleProperties;
-    let props = Object.create(ownerProperties || null);
-    let hostAndRootProps = StyleProperties$1.hostAndRootPropertiesForScope(host, styleInfo.styleRules);
-    let propertyData = StyleProperties$1.propertyDataFromStyles(ownerStyleInfo.styleRules, host);
-    let propertiesMatchingHost = propertyData.properties;
-    Object.assign(
-      props,
-      hostAndRootProps.hostProps,
-      propertiesMatchingHost,
-      hostAndRootProps.rootProps
-    );
-    this._mixinOverrideStyles(props, styleInfo.overrideStyleProperties);
-    StyleProperties$1.reify(props);
-    styleInfo.styleProperties = props;
-  }
-  _mixinOverrideStyles(props, overrides) {
-    for (let p in overrides) {
-      let v = overrides[p];
-      // skip override props if they are not truthy or 0
-      // in order to fall back to inherited values
-      if (v || v === 0) {
-        props[p] = v;
-      }
-    }
-  }
-  /**
-   * Update styles of the whole document
-   *
-   * @param {Object=} properties
-   */
-  styleDocument(properties) {
-    this.styleSubtree(this._documentOwner, properties);
-  }
-  /**
-   * Update styles of a subtree
-   *
-   * @param {!HTMLElement} host
-   * @param {Object=} properties
-   */
-  styleSubtree(host, properties) {
-    let root = host.shadowRoot;
-    if (root || this._isRootOwner(host)) {
-      this.styleElement(host, properties);
-    }
-    // process the shadowdom children of `host`
-    let shadowChildren = root && (root.children || root.childNodes);
-    if (shadowChildren) {
-      for (let i = 0; i < shadowChildren.length; i++) {
-        let c = /** @type {!HTMLElement} */(shadowChildren[i]);
-        this.styleSubtree(c);
-      }
-    } else {
-      // process the lightdom children of `host`
-      let children = host.children || host.childNodes;
-      if (children) {
-        for (let i = 0; i < children.length; i++) {
-          let c = /** @type {!HTMLElement} */(children[i]);
-          this.styleSubtree(c);
-        }
-      }
-    }
-  }
-  /* Custom Style operations */
-  _revalidateCustomStyleApplyShim(customStyles) {
-    for (let i = 0; i < customStyles.length; i++) {
-      let c = customStyles[i];
-      let s = this._customStyleInterface['getStyleForCustomStyle'](c);
-      if (s) {
-        this._revalidateApplyShim(s);
-      }
-    }
-  }
-  _applyCustomStyles(customStyles) {
-    for (let i = 0; i < customStyles.length; i++) {
-      let c = customStyles[i];
-      let s = this._customStyleInterface['getStyleForCustomStyle'](c);
-      if (s) {
-        StyleProperties$1.applyCustomStyle(s, this._documentOwnerStyleInfo.styleProperties);
-      }
-    }
-  }
-  transformCustomStyleForDocument(style) {
-    let ast = rulesForStyle(style);
-    forEachRule(ast, (rule) => {
-      if (nativeShadow) {
-        StyleTransformer$1.normalizeRootSelector(rule);
-      } else {
-        StyleTransformer$1.documentRule(rule);
-      }
-      if (nativeCssVariables) {
-        this._ensure();
-        this._applyShim['transformRule'](rule);
-      }
-    });
-    if (nativeCssVariables) {
-      style.textContent = toCssText(ast);
-    } else {
-      this._documentOwnerStyleInfo.styleRules.rules.push(ast);
-    }
-  }
-  _revalidateApplyShim(style) {
-    if (nativeCssVariables) {
-      let ast = rulesForStyle(style);
-      this._ensure();
-      this._applyShim['transformRules'](ast);
-      style.textContent = toCssText(ast);
-    }
-  }
-  getComputedStyleValue(element, property) {
-    let value;
-    if (!nativeCssVariables) {
-      // element is either a style host, or an ancestor of a style host
-      let styleInfo = StyleInfo.get(element) || StyleInfo.get(this._styleOwnerForNode(element));
-      value = styleInfo.styleProperties[property];
-    }
-    // fall back to the property value from the computed styling
-    value = value || window.getComputedStyle(element).getPropertyValue(property);
-    // trim whitespace that can come after the `:` in css
-    // example: padding: 2px -> " 2px"
-    return value ? value.trim() : '';
-  }
-  // given an element and a classString, replaces
-  // the element's class with the provided classString and adds
-  // any necessary ShadyCSS static and property based scoping selectors
-  setElementClass(element, classString) {
-    let root = element.getRootNode();
-    let classes = classString ? classString.split(/\s/) : [];
-    let scopeName = root.host && root.host.localName;
-    // If no scope, try to discover scope name from existing class.
-    // This can occur if, for example, a template stamped element that
-    // has been scoped is manipulated when not in a root.
-    if (!scopeName) {
-      var classAttr = element.getAttribute('class');
-      if (classAttr) {
-        let k$ = classAttr.split(/\s/);
-        for (let i=0; i < k$.length; i++) {
-          if (k$[i] === StyleTransformer$1.SCOPE_NAME) {
-            scopeName = k$[i+1];
-            break;
-          }
-        }
-      }
-    }
-    if (scopeName) {
-      classes.push(StyleTransformer$1.SCOPE_NAME, scopeName);
-    }
-    if (!nativeCssVariables) {
-      let styleInfo = StyleInfo.get(element);
-      if (styleInfo && styleInfo.scopeSelector) {
-        classes.push(StyleProperties$1.XSCOPE_NAME, styleInfo.scopeSelector);
-      }
-    }
-    setElementClassRaw(element, classes.join(' '));
-  }
-  _styleInfoForNode(node) {
-    return StyleInfo.get(node);
-  }
-}
-
-/* exports */
-ScopingShim.prototype['flush'] = ScopingShim.prototype.flush;
-ScopingShim.prototype['prepareTemplate'] = ScopingShim.prototype.prepareTemplate;
-ScopingShim.prototype['styleElement'] = ScopingShim.prototype.styleElement;
-ScopingShim.prototype['styleDocument'] = ScopingShim.prototype.styleDocument;
-ScopingShim.prototype['styleSubtree'] = ScopingShim.prototype.styleSubtree;
-ScopingShim.prototype['getComputedStyleValue'] = ScopingShim.prototype.getComputedStyleValue;
-ScopingShim.prototype['setElementClass'] = ScopingShim.prototype.setElementClass;
-ScopingShim.prototype['_styleInfoForNode'] = ScopingShim.prototype._styleInfoForNode;
-ScopingShim.prototype['transformCustomStyleForDocument'] = ScopingShim.prototype.transformCustomStyleForDocument;
-ScopingShim.prototype['getStyleAst'] = ScopingShim.prototype.getStyleAst;
-ScopingShim.prototype['styleAstToString'] = ScopingShim.prototype.styleAstToString;
-ScopingShim.prototype['flushCustomStyles'] = ScopingShim.prototype.flushCustomStyles;
-Object.defineProperties(ScopingShim.prototype, {
-  'nativeShadow': {
-    get() {
-      return nativeShadow;
-    }
-  },
-  'nativeCss': {
-    get() {
-      return nativeCssVariables;
-    }
-  }
-});
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-
-/** @const {ScopingShim} */
-const scopingShim$1 = new ScopingShim();
-
-let ApplyShim;
-let CustomStyleInterface;
-
-if (window['ShadyCSS']) {
-  ApplyShim = window['ShadyCSS']['ApplyShim'];
-  CustomStyleInterface = window['ShadyCSS']['CustomStyleInterface'];
-}
-
-window.ShadyCSS = {
-  ScopingShim: scopingShim$1,
-  /**
-   * @param {!HTMLTemplateElement} template
-   * @param {string} elementName
-   * @param {string=} elementExtends
-   */
-  prepareTemplate(template, elementName, elementExtends) {
-    scopingShim$1.flushCustomStyles();
-    scopingShim$1.prepareTemplate(template, elementName, elementExtends);
-  },
-
-  /**
-   * @param {!HTMLElement} element
-   * @param {Object=} properties
-   */
-  styleSubtree(element, properties) {
-    scopingShim$1.flushCustomStyles();
-    scopingShim$1.styleSubtree(element, properties);
-  },
-
-  /**
-   * @param {!HTMLElement} element
-   */
-  styleElement(element) {
-    scopingShim$1.flushCustomStyles();
-    scopingShim$1.styleElement(element);
-  },
-
-  /**
-   * @param {Object=} properties
-   */
-  styleDocument(properties) {
-    scopingShim$1.flushCustomStyles();
-    scopingShim$1.styleDocument(properties);
-  },
-
-  /**
-   * @param {Element} element
-   * @param {string} property
-   * @return {string}
-   */
-  getComputedStyleValue(element, property) {
-    return scopingShim$1.getComputedStyleValue(element, property);
-  },
-
-  nativeCss: nativeCssVariables,
-
-  nativeShadow: nativeShadow
-};
-
-if (ApplyShim) {
-  window.ShadyCSS.ApplyShim = ApplyShim;
-}
-
-if (CustomStyleInterface) {
-  window.ShadyCSS.CustomStyleInterface = CustomStyleInterface;
-}
-
-/**
- * @license
- * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
- * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
- * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
- * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
- * Code distributed by Google as part of the polymer project is also
- * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
- */
-
-(function() {
-
-  'use strict';
-
-  var customElements = window['customElements'];
-  var HTMLImports = window['HTMLImports'];
-
-  if (customElements && customElements['polyfillWrapFlushCallback']) {
-    // Here we ensure that the public `HTMLImports.whenReady`
-    // always comes *after* custom elements have upgraded.
-    var flushCallback;
-    var runAndClearCallback = function runAndClearCallback() {
-      if (flushCallback) {
-        var cb = flushCallback;
-        flushCallback = null;
-        cb();
-        return true;
-      }
-    };
-    var origWhenReady = HTMLImports['whenReady'];
-    customElements['polyfillWrapFlushCallback'](function(cb) {
-      flushCallback = cb;
-      origWhenReady(runAndClearCallback);
-    });
-
-    HTMLImports['whenReady'] = function(cb) {
-      origWhenReady(function() {
-        // custom element code may add dynamic imports
-        // to match processing of native custom elements before
-        // domContentLoaded, we wait for these imports to resolve first.
-        if (runAndClearCallback()) {
-          HTMLImports['whenReady'](cb);
-        } else {
-          cb();
-        }
-      });
-    };
-
-  }
-
-  HTMLImports['whenReady'](function() {
-    requestAnimationFrame(function() {
-      window.dispatchEvent(new CustomEvent('WebComponentsReady'));
-    });
-  });
-
-})();
-
-/**
- * @license
- * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
- * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
- * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
- * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
- * Code distributed by Google as part of the polymer project is also
- * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
- */
-
-(function() {
-  'use strict';
-  // It's desireable to provide a default stylesheet
-  // that's convenient for styling unresolved elements, but
-  // it's cumbersome to have to include this manually in every page.
-  // It would make sense to put inside some HTMLImport but
-  // the HTMLImports polyfill does not allow loading of stylesheets
-  // that block rendering. Therefore this injection is tolerated here.
-  //
-  // NOTE: position: relative fixes IE's failure to inherit opacity
-  // when a child is not statically positioned.
-  var style = document.createElement('style');
-  style.textContent = ''
-      + 'body {'
-      + 'transition: opacity ease-in 0.2s;'
-      + ' } \n'
-      + 'body[unresolved] {'
-      + 'opacity: 0; display: block; overflow: hidden; position: relative;'
-      + ' } \n'
-      ;
-  var head = document.querySelector('head');
-  head.insertBefore(style, head.firstChild);
-
-})();
-
-/**
-@license
-Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-*/
-/*
- * Polyfills loaded: HTML Imports, Custom Elements, Shady DOM/Shady CSS, platform polyfills, template
- * Used in: IE 11
- */
-
-}());