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".
+      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;
   }
 }