Disallow mixing in classes that use 'super'.

sdk/lib/_internal/compiler/implementation/world.dart

Index: sdk/lib/_internal/compiler/implementation/world.dart
diff --git a/sdk/lib/_internal/compiler/implementation/world.dart b/sdk/lib/_internal/compiler/implementation/world.dart
index 9cdaea8251d52fe3751e213fc0ddeeb5f9c3e085..a40050ee801e7910e496a722dcb0bc2c4156d50c 100644
--- a/sdk/lib/_internal/compiler/implementation/world.dart
+++ b/sdk/lib/_internal/compiler/implementation/world.dart
@@ -7,6 +7,7 @@ part of dart2js;
 class World {
   final Compiler compiler;
   final Map<ClassElement, Set<ClassElement>> subtypes;
+  final Map<ClassElement, Set<MixinApplicationElement>> mixinUses;
   final Map<ClassElement, Set<ClassElement>> typesImplementedBySubclasses;
   final Set<ClassElement> classesNeedingRti;
   final Map<ClassElement, Set<ClassElement>> rtiDependencies;
@@ -15,6 +16,7 @@ class World {
 
   World(Compiler compiler)
       : subtypes = new Map<ClassElement, Set<ClassElement>>(),
+        mixinUses = new Map<ClassElement, Set<MixinApplicationElement>>(),
         typesImplementedBySubclasses =
             new Map<ClassElement, Set<ClassElement>>(),
         userDefinedGetters = new FunctionSet(compiler),
@@ -93,6 +95,14 @@ class World {
     return classesNeedingRti.contains(cls) || compiler.enabledRuntimeType;
   }
 
+  void registerMixinUse(MixinApplicationElement mixinApplication,
+                        ClassElement mixin) {
+    Set<MixinApplicationElement> users =
+        mixinUses.putIfAbsent(mixin, () =>
+                              new Set<MixinApplicationElement>());
+    users.add(mixinApplication);
+  }
+
   void registerRtiDependency(Element element, Element dependency) {
     // We're not dealing with typedef for now.
     if (!element.isClass() || !dependency.isClass()) return;
@@ -133,8 +143,6 @@ class World {
     return subclasses == null || subclasses.isEmpty;
   }
 
-
-
   void registerUsedElement(Element element) {
     if (element.isMember()) {
       if (element.isGetter()) {