Make mixins work on native classes.

sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart b/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
index b2ad0686849ba4ab0dd2c63c6b335a1026f6048b..97f703b1e362237e3ad7798259d35622ec485380 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
@@ -1171,21 +1171,6 @@ class CodeEmitterTask extends CompilerTask {
       }
     }
 
-    // TODO(kasperl): We should make sure to only emit one version of
-    // overridden methods. Right now, we rely on the ordering so the
-    // methods pulled in from mixins are replaced with the members
-    // from the class definition.
-
-    // If the class is a native class, we have to add the instance
-    // members defined in the non-native mixin applications used by
-    // the class.
-    visitNativeMixins(classElement, (MixinApplicationElement mixin) {
-      mixin.forEachMember(
-          visitMember,
-          includeBackendMembers: true,
-          includeSuperMembers: false);
-    });
-
     classElement.implementation.forEachMember(
         visitMember,
         includeBackendMembers: true,
@@ -1296,22 +1281,6 @@ class CodeEmitterTask extends CompilerTask {
     }
   }
 
-  void visitNativeMixins(ClassElement classElement,
-                         void visit(MixinApplicationElement mixinApplication)) {
-    if (!classElement.isNative()) return;
-    // Use recursion to make sure to visit the superclasses before the
-    // subclasses. Once we start keeping track of the emitted fields
-    // and members, we're going to want to visit these in the other
-    // order so we get the most specialized definition first.
-    void recurse(ClassElement cls) {
-      if (cls == null || !cls.isMixinApplication) return;
-      recurse(cls.superclass);
-      assert(!cls.isNative());
-      visit(cls);
-    }
-    recurse(classElement.superclass);
-  }
-
   /**
    * Documentation wanted -- johnniwinther
    *
@@ -1389,15 +1358,6 @@ class CodeEmitterTask extends CompilerTask {
     // fields pulled in from mixins are replaced with the fields from
     // the class definition.
 
-    // If the class is a native class, we have to add the fields
-    // defined in the non-native mixin applications used by the class.
-    visitNativeMixins(classElement, (MixinApplicationElement mixin) {
-      mixin.forEachInstanceField(
-          visitField,
-          includeBackendMembers: true,
-          includeSuperMembers: false);
-    });
-
     // If a class is not instantiated then we add the field just so we can
     // generate the field getter/setter dynamically. Since this is only
     // allowed on fields that are in [classElement] we don't need to visit
@@ -1405,7 +1365,7 @@ class CodeEmitterTask extends CompilerTask {
     classElement.implementation.forEachInstanceField(
         visitField,
         includeBackendMembers: true,
-        includeSuperMembers: isInstantiated && !classElement.isNative());
+        includeSuperMembers: isInstantiated);
   }
 
   void generateGetter(Element member, String fieldName, String accessorName,
@@ -1590,12 +1550,7 @@ class CodeEmitterTask extends CompilerTask {
     needsDefineClass = true;
     String className = namer.getName(classElement);
 
-    // Find the first non-native superclass.
     ClassElement superclass = classElement.superclass;
-    while (superclass != null && superclass.isNative()) {
-      superclass = superclass.superclass;
-    }
-
     String superName = "";
     if (superclass != null) {
       superName = namer.getName(superclass);
@@ -1725,17 +1680,6 @@ class CodeEmitterTask extends CompilerTask {
       generateInterfacesIsTests(interfaceType.element, emitIsTest,
                                 emitSubstitution, generated);
     }
-
-    // For native classes, we also have to run through their mixin
-    // applications and make sure we deal with 'is' tests correctly
-    // for those.
-    visitNativeMixins(cls, (MixinApplicationElement mixin) {
-      for (DartType interfaceType in mixin.interfaces) {
-        ClassElement interfaceElement = interfaceType.element;
-        generateInterfacesIsTests(interfaceType.element, emitIsTest,
-                                  emitSubstitution, generated);
-      }
-    });
   }
 
   /**