[polymer] interop with polymer-element and polymer.js

pkg/polymer/test/noscript_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:unittest/unittest.dart';
 import 'package:unittest/html_config.dart';
 import 'package:polymer/polymer.dart';
 import 'package:template_binding/template_binding.dart';
@@ skipping 12 matching lines @@
 
   var ready = Polymer.onReady.then((_) {
     var a = querySelector("#a");
     templateBind(a).model = "foo";
     return onMutation(a.parent);
   });
 
   setUp(() => ready);
 
   test('template found with multiple noscript declarations', () {
-    expect(querySelector('x-a') is PolymerElement, isTrue);
     expect(querySelector('x-a').shadowRoot.nodes.first.text, 'a');
-
-    expect(querySelector('x-c') is PolymerElement, isTrue);
     expect(querySelector('x-c').shadowRoot.nodes.first.text, 'c');
-
-    expect(querySelector('x-b') is PolymerElement, isTrue);
     expect(querySelector('x-b').shadowRoot.nodes.first.text, 'b');
-
-    expect(querySelector('x-d') is PolymerElement, isTrue);
     expect(querySelector('x-d').shadowRoot.nodes.first.text, 'd');
   });
 });