feat(building-rollup): avoid helper chunk in modern build

packages/building-rollup/src/babel/babel-configs.js

@@ -4,6 +4,25 @@ const { isFalsy } = require('../utils');
 const createBabelConfigRollupBuild = ({ developmentMode, rootDir }) => ({
   babelHelpers: 'bundled',
   compact: true,
+  presets: [
+    [
+      require.resolve('@babel/preset-env'),
+      {
+        targets: [
+          'last 3 Chrome major versions',
+          'last 3 ChromeAndroid major versions',
+          'last 3 Firefox major versions',
+          'last 3 Edge major versions',
+          'last 3 Safari major versions',
+          'last 3 iOS major versions',
+        ],
+        useBuiltIns: false,
+        shippedProposals: true,
+        modules: false,
+        bugfixes: true,
+      },
+    ],
+  ],
   plugins: [
     // rollup doesn't support optional chaining yet, so we compile it during input
     [require.resolve('@babel/plugin-proposal-optional-chaining'), { loose: true }],

packages/building-rollup/src/createBasicConfig.js

@@ -7,7 +7,6 @@ const { babel, getBabelOutputPlugin } = require('@rollup/plugin-babel');
 const merge = require('deepmerge');
 const {
   createBabelConfigRollupBuild,
-  babelConfigRollupGenerate,
   babelConfigLegacyRollupGenerate,
   babelConfigSystemJs,
 } = require('./babel/babel-configs');
@@ -42,12 +41,7 @@ function createBasicConfig(userOptions = {}) {
       assetFileNames: assetName,
       format: 'es',
       dir: opts.outputDir,
-      plugins: [
-        // build to js supported by modern browsers
-        getBabelOutputPlugin(babelConfigRollupGenerate),
-        // create babel-helpers chunk based on es5 build
-        bundledBabelHelpers({ minify: !developmentMode }),
-      ],
+      plugins: [],
     },
 
     plugins: [
@@ -58,8 +52,7 @@ function createBasicConfig(userOptions = {}) {
         },
       }),
 
-      // build non-standard syntax to standard syntax and other babel optimization plugins
-      // user plugins are deduped to allow overriding
+      // run babel, compiling down to latest of modern browsers
       dedupedBabelPlugin(
         babel,
         opts.babel,
@@ -82,6 +75,8 @@ function createBasicConfig(userOptions = {}) {
         entryFileNames: `nomodule-${fileName}`,
         chunkFileNames: `nomodule-${fileName}`,
         assetFileNames: `nomodule-${assetName}`,
+        // in the legacy build we want to build to es5, but the babel plugin in the input plugins runs for both
+        // we add output plugins here only for the legacy build to build to es5
         plugins: [
           // buid to es5
           getBabelOutputPlugin(babelConfigLegacyRollupGenerate),