dart2js: Use an abstract Name class for names in the generated JavaScript ast.

sdk/lib/_internal/compiler/js_lib/js_mirrors.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.
 
 library dart._js_mirrors;
 
 import 'dart:_js_embedded_names' show
     JsGetName,
     ALL_CLASSES,
     LAZIES,
@@ skipping 1966 matching lines @@
 
   ClassMirror get superclass {
     if (_superclass == null) {
       var typeInformationContainer = JS_EMBEDDED_GLOBAL('', TYPE_INFORMATION);
       List<int> typeInformation =
           JS('List|Null', '#[#]', typeInformationContainer, _mangledName);
       if (typeInformation != null) {
         var type = getType(typeInformation[0]);
         _superclass = typeMirrorFromRuntimeTypeRepresentation(this, type);
       } else {
-        var superclassName = _fieldsDescriptor.split(';')[0];
+        var superclassName = _fieldsDescriptor.split(';')[0].split(':')[0];
         // TODO(zarah): Remove special handing of mixins.
         var mixins = superclassName.split('+');
         if (mixins.length > 1) {
           if (mixins.length != 2) {
             throw new RuntimeError('Strange mixin: $_fieldsDescriptor');
           }
           _superclass = reflectClassByMangledName(mixins[0]);
         } else {
           // Use _superclass == this to represent class with no superclass
           // (Object).
@@ skipping 1048 matching lines @@
   // have a part (following a '.') that starts with '_'.
   const int UNDERSCORE = 0x5f;
   if (name.isEmpty) return true;
   int index = -1;
   do {
     if (name.codeUnitAt(index + 1) == UNDERSCORE) return false;
     index = name.indexOf('.', index + 1);
   } while (index >= 0 && index + 1 < name.length);
   return true;
 }