update to polymer js 0.5.1

pkg/polymer/test/prop_attr_reflection_test.dart

 // Copyright (c) 2014, 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.
 
 import 'dart:async';
 import 'dart:html';
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_config.dart';
 import 'package:polymer/polymer.dart';
 
@@ skipping 158 matching lines @@
       expect(xbar.attributes['obj'], 'hi', reason:
           'reflect property based on current type');
 
       expect(xzot.str, 'str2');
       expect(xzot.zot, 2);
       xzot.str = 'hello';
       xzot.zot = 5;
     }).then((_) => onAttributeChange(xzot)).then((_) {
       expect(xzot.attributes['str'], xzot.str);
       // TODO(jmesserly): the JS test seems backwards of the description text.
-      // Is it because it doesn't do "Platform.flush()"?
+      // Is it because it doesn't do "WebComponents.flush()"?
       expect(xzot.attributes['zot'], '5',
           reason: 'extendee reflect false not honored');
     });
   });
 });