attempt to reduce IE flakiness in template_bind_test

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:collection';
 import 'dart:html';
 import 'dart:math' as math;
@@ skipping 1159 matching lines @@
         '</template>');
 
     var m = toObservable({
       'selected': 1,
       'groups': [{
         'name': 'one', 'items': [{ 'val': 0 }, { 'val': 1 }]
       }],
     });
 
     recursivelySetTemplateModel(div, m);
+
+    var completer = new Completer();
+
+    new MutationObserver((records, observer) {
+      var select = div.nodes[0].nextNode;
+      if (select == null || select.querySelector('option') == null) return;
+
+      observer.disconnect();
+      new Future(() {
+        expect(select.nodes.length, 2);
+
+        expect(select.selectedIndex, 1, reason: 'selected index should update '
+            'after template expands.');
+
+        expect(select.nodes[0].tagName, 'TEMPLATE');
+        expect((templateBind(templateBind(select.nodes[0]).ref)
+            .content.nodes[0] as Element).tagName, 'OPTGROUP');
+
+        var optgroup = select.nodes[1];
+        expect(optgroup.nodes[0].tagName, 'TEMPLATE');
+        expect(optgroup.nodes[1].tagName, 'OPTION');
+        expect(optgroup.nodes[1].text, '0');
+        expect(optgroup.nodes[2].tagName, 'OPTION');
+        expect(optgroup.nodes[2].text, '1');
+
+        completer.complete();
+      });
+    })..observe(div, childList: true, subtree: true);
+
     Observable.dirtyCheck();
 
-    // Use a timer so it's slower than mutation observers.
-    return new Future(() {
-      var select = div.nodes[0].nextNode;
-      expect(select.nodes.length, 2);
-
-      expect(select.selectedIndex, 1, reason: 'selected index should update by '
-          'animationFrame time');
-
-      expect(select.nodes[0].tagName, 'TEMPLATE');
-      expect((templateBind(templateBind(select.nodes[0]).ref)
-          .content.nodes[0] as Element).tagName, 'OPTGROUP');
-
-      var optgroup = select.nodes[1];
-      expect(optgroup.nodes[0].tagName, 'TEMPLATE');
-      expect(optgroup.nodes[1].tagName, 'OPTION');
-      expect(optgroup.nodes[1].text, '0');
-      expect(optgroup.nodes[2].tagName, 'OPTION');
-      expect(optgroup.nodes[2].text, '1');
-    });
+    return completer.future;
   });
 
   observeTest('NestedIterateTableMixedSemanticNative', () {
     if (!parserHasNativeTemplate) return;
 
     var div = createTestHtml(
         '<table><tbody>'
           '<template repeat="{{}}">'
             '<tr>'
               '<td template repeat="{{}}" class="{{ val }}">{{ val }}</td>'
@@ skipping 655 matching lines @@
   prepareBinding(path, name, node) {
     if (name != 'text' || path != 'age') return null;
 
     return (model, node) {
       expect(model['age'], expectedAge);
       count++;
       return model;
     };
   }
 }