Redo "Revert "Encode super calls via extra properties on prototypes.""

pkg/compiler/lib/src/js_backend/backend.dart

Index: pkg/compiler/lib/src/js_backend/backend.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend.dart b/pkg/compiler/lib/src/js_backend/backend.dart
index d4585d54373e2bc025277122f4076b8ed1f6117c..627a7c05419b5d04a12ffa77b6992acfce0a7486 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -331,12 +331,6 @@ class JavaScriptBackend extends Backend {
    */
   final Set<ClassElement> specialOperatorEqClasses = new Set<ClassElement>();
 
-  /**
-   * A set of members that are called from subclasses via super.
-   */
-  final Set<FunctionElement> aliasedSuperMembers =
-      new Setlet<FunctionElement>();
-
   List<CompilerTask> get tasks {
     List<CompilerTask> result = functionCompiler.tasks;
     result.add(emitter);
@@ -544,20 +538,6 @@ class JavaScriptBackend extends Backend {
     return name;
   }
 
-  /**
-   * Record that [method] is called from a subclass via `super`.
-   */
-  void registerAliasedSuperMember(FunctionElement method) {
-    aliasedSuperMembers.add(method);
-  }
-
-  /**
-   * Returns `true` is [member] is called from a subclass via `super`.
-   */
-  bool isAliasedSuperMember(FunctionElement member) {
-    return aliasedSuperMembers.contains(member);
-  }
-
   bool isInterceptedMethod(Element element) {
     if (!element.isInstanceMember) return false;
     if (element.isGenerativeConstructorBody) {
@@ -2261,7 +2241,6 @@ class JavaScriptBackend extends Backend {
   void forgetElement(Element element) {
     constants.forgetElement(element);
     constantCompilerTask.dartConstantCompiler.forgetElement(element);
-    aliasedSuperMembers.remove(element);
   }
 
   void registerMainHasArguments(Enqueuer enqueuer) {