fix template_binding tests on safari/ie

pkg/template_binding/test/element_bindings_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.element_bindings_test;
 
 import 'dart:html';
 import 'package:observe/observe.dart';
 import 'package:template_binding/template_binding.dart';
 import 'package:unittest/html_config.dart';
@@ skipping 86 matching lines @@
   observeTest('PlaceHolderBindingText', () {
     var model = toObservable({
       'adj': 'cruel',
       'noun': 'world'
     });
 
     var el = new DivElement();
     el.text = 'dummy';
     el.nodes.first.text = 'Hello {{ adj }} {{noun}}!';
     var template = new Element.html('<template bind>');
-    template.content.append(el);
+    templateBind(template).content.append(el);
     testDiv.append(template);
     templateBind(template).model = model;
 
     performMicrotaskCheckpoint();
     el = testDiv.nodes[1].nodes.first;
     expect(el.text, 'Hello cruel world!');
 
     model['adj'] = 'happy';
     performMicrotaskCheckpoint();
     expect(el.text, 'Hello happy world!');
@@ skipping 258 matching lines @@
     expect(select.selectedIndex, 2);
 
     select.selectedIndex = 1;
     dispatchEvent('change', select);
     expect(model['val'], 1);
   });
 
   observeTest('MultipleReferences', () {
     var el = new DivElement();
     var template = new Element.html('<template bind>');
-    template.content.append(el);
+    templateBind(template).content.append(el);
     testDiv.append(template);
 
     var model = toObservable({'foo': 'bar'});
     el.attributes['foo'] = '{{foo}} {{foo}}';
     templateBind(template).model = model;
 
     performMicrotaskCheckpoint();
     el = testDiv.nodes[1];
     expect(el.attributes['foo'], 'bar bar');
   });
 }