fix template_binding tests on safari/ie

pkg/template_binding/test/element_bindings_test.dart

Index: pkg/template_binding/test/element_bindings_test.dart
diff --git a/pkg/template_binding/test/element_bindings_test.dart b/pkg/template_binding/test/element_bindings_test.dart
index 25d0289b45894893aa0ffd5100dfcff899f82c98..56c42c485ebc30d27cca918cf58e94117f4d48e9 100644
--- a/pkg/template_binding/test/element_bindings_test.dart
+++ b/pkg/template_binding/test/element_bindings_test.dart
@@ -104,7 +104,7 @@ elementBindingTests() {
     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;
 
@@ -383,7 +383,7 @@ elementBindingTests() {
   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'});