Revert "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 4f0b8643ef6ee00c71d366fe0876505935364d73..d4585d54373e2bc025277122f4076b8ed1f6117c 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -331,6 +331,12 @@ 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);
@@ -538,6 +544,20 @@ 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) {