update polymer js to 0.4.0

pkg/template_binding/test/template_binding_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.
 
 library template_binding.test.template_binding_test;
 
 import 'dart:async';
 import 'dart:html';
 import 'dart:js' show JsObject;
 import 'dart:math' as math;
@@ skipping 1351 matching lines @@
         '<template ref=A repeat></template>');
 
     var template = div.nodes[2];
     var model = new ObservableList.from(['Fry']);
     templateBind(template).model = model;
 
     return new Future(() {
       expect(div.nodes.length, 4);
       expect('Hi, Fry', div.nodes[3].text);
 
-      div.nodes[2].attributes['ref'] = 'B';
+      // In IE 11, MutationObservers do not fire before setTimeout.
+      // So rather than using "then" to queue up the next test, we use a
+      // MutationObserver here to detect the change to "ref".

[Siggi Cherem (dart-lang), 2014/09/09 21:21:43]

what if we use endOfMicrotask instead? or is that too soon?

[jakemac, 2014/09/10 16:30:00]

I think its best to keep this in sync with the js side, it sounds like they were
having issues with their version of endOfMicrotask so that is why they changed
it here.

+      var done = new Completer();
+      new MutationObserver((mutations, observer) {
+        expect(div.nodes.length, 5);
+
+        expect('Hola, Fry', div.nodes[3].text);
+        expect('Hola, Leela', div.nodes[4].text);
+        done.complete();
+      }).observe(template, attributes: true, attributeFilter: ['ref']);
+
+      template.setAttribute('ref', 'B');
       model.add('Leela');
 
-    }).then(nextMicrotask).then((x) {
-      expect(div.nodes.length, 5);
-
-      expect('Hola, Fry', div.nodes[3].text);
-      expect('Hola, Leela', div.nodes[4].text);
+      return done.future;
     });
   });
 
   test('Bound Ref', () {
     var div = createTestHtml(
         '<template id=A>Hi, {{}}</template>'
         '<template id=B>Hola, {{}}</template>'
         '<template ref="{{ ref }}" repeat="{{ people }}"></template>');
 
     var template = div.nodes[2];
@@ skipping 1332 matching lines @@
 class TestAccessorModel extends Observable {
   @observable var value = 1;
   var count = 0;
 
   @reflectable
   get prop {
     count++;
     return value;
   }
 }