dart2js: Don't reference mixins when they are only used for RTI.

pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart2js.js_emitter;
 
 class ClassEmitter extends CodeEmitterHelper {
 
   ClassStubGenerator get _stubGenerator =>
       new ClassStubGenerator(compiler, namer, backend);
@@ skipping 14 matching lines @@
 
     emitter.needsClassSupport = true;
     String className = namer.getNameOfClass(classElement);
 
     ClassElement superclass = classElement.superclass;
     String superName = "";
     if (superclass != null) {
       superName = namer.getNameOfClass(superclass);
     }
 
-    if (classElement.isMixinApplication) {
+    if (classElement.isMixinApplication && !onlyForRti) {
       String mixinName = namer.getNameOfClass(computeMixinClass(classElement));
       superName = '$superName+$mixinName';
       emitter.needsMixinSupport = true;
     }
 
     ClassBuilder builder = new ClassBuilder(classElement, namer);
     builder.superName = superName;
     emitClassConstructor(classElement, builder, onlyForRti: onlyForRti);
     emitFields(classElement, builder, onlyForRti: onlyForRti);
     emitClassGettersSetters(classElement, builder, onlyForRti: onlyForRti);
@@ skipping 548 matching lines @@
           js(r'this.$builtinTypeInfo && this.$builtinTypeInfo[#]', index);
     }
     jsAst.Expression convertRtiToRuntimeType = emitter
         .staticFunctionAccess(backend.findHelper('convertRtiToRuntimeType'));
     compiler.dumpInfoTask.registerElementAst(element,
         builder.addProperty(name,
             js('function () { return #(#) }',
                 [convertRtiToRuntimeType, computeTypeVariable])));
   }
 }