introduce web_components pkg for consolidated polyfills

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';
 
-main() {
-  initPolymer();
+Future<List<MutationRecord>> onMutation(Node node) {
+  var completer = new Completer();
+  new MutationObserver((mutations, observer) {
+    observer.disconnect();
+    completer.complete(mutations);
+  })..observe(node, childList: true, subtree: true);
+  return completer.future;
+}
+
+main() => initPolymer().run(() {
   useHtmlConfiguration();
-  templateBind(querySelector("#a")).model = "foo";
 
-  setUp(() => Polymer.onReady);
+  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');
   });
-}
+});