update polymer js to 0.4.0

pkg/polymer/test/template_distribute_dynamic_test.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.
 
 import 'dart:async';
 import 'dart:html';
 import 'package:polymer/polymer.dart';
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_config.dart';
 
@@ skipping 21 matching lines @@
     return new Future(() {
       // tickle SD polyfill
       offsetHeight;
       var children = this.$['echo'].children;
       expect(children[0].localName, 'template', reason:
           'shadowDOM dynamic distribution via template');
       expect(children[1].text, 'foo', reason:
           'shadowDOM dynamic distribution via template');
       expect(children[2].text, 'bar', reason:
           'shadowDOM dynamic distribution via template');
-
-      // TODO(jmesserly): restore this if we get the JS interop capability.
-      /*
-      if (window.ShadowDOMPolyfill) {
-        var actualChildren = this.$.echo.impl.children;
-        chai.assert.equal(actualChildren.length, 4,
-          'shadowDOMPolyfill distributes expected number of actual children.');
-      }
-      */
+      expect(children.length, 3, reason: 'expected number of children');
     });
   }
 }
 
 main() => initPolymer().run(() {
   useHtmlConfiguration();
 
   setUp(() => Polymer.onReady);
 
   test('inserted called', () => (querySelector('x-test') as XTest).onTestDone);
 });