show context when invoking Show Implementations from Find Usages popup

#KT-13475 Fixed

idea/src/META-INF/plugin.xml

@@ -733,6 +733,8 @@
 
     <nameSuggestionProvider implementation="org.jetbrains.kotlin.idea.core.KotlinNameSuggestionProvider"/>
 
+    <usageToPsiElementProvider implementation="org.jetbrains.kotlin.idea.codeInsight.KotlinUsageToPsiElementProvider"/>
+
     <intentionAction>
       <className>org.jetbrains.kotlin.idea.intentions.IfNullToElvisIntention</className>
       <category>Kotlin</category>

idea/src/org/jetbrains/kotlin/idea/codeInsight/KotlinUsageToPsiElementProvider.kt

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.idea.codeInsight
+
+import com.intellij.psi.PsiElement
+import com.intellij.usages.UsageToPsiElementProvider
+import org.jetbrains.kotlin.idea.KotlinLanguage
+import org.jetbrains.kotlin.psi.KtImportDirective
+import org.jetbrains.kotlin.psi.KtNamedDeclaration
+import org.jetbrains.kotlin.psi.psiUtil.parentsWithSelf
+
+class KotlinUsageToPsiElementProvider : UsageToPsiElementProvider() {
+    override fun getAppropriateParentFrom(element: PsiElement): PsiElement? {
+        if (element.language == KotlinLanguage.INSTANCE) {
+            return element.parentsWithSelf.first { it is KtNamedDeclaration || it is KtImportDirective }
+        }
+        return null
+    }
+}