use .append instead of .nodes.add

tests/html/shadow_dom_test.dart

 // Copyright (c) 2011, 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 ShadowDOMTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 
 main() {
@@ skipping 10 matching lines @@
     var div1, div2, shadowRoot, paragraph1, paragraph2;
 
     init() {
       paragraph1 = new ParagraphElement();
       paragraph2 = new ParagraphElement();
       [paragraph1, paragraph2].forEach((p) { p.classes.add('foo');});
       div1 = new DivElement();
       div2 = new DivElement();
       div1.classes.add('foo');
       shadowRoot = div2.createShadowRoot();
-      shadowRoot.nodes.add(paragraph1);
-      shadowRoot.nodes.add(new ContentElement());
-      div2.nodes.add(paragraph2);
-      document.body.nodes.add(div1);
-      document.body.nodes.add(div2);
+      shadowRoot.append(paragraph1);
+      shadowRoot.append(new ContentElement());
+      div2.append(paragraph2);
+      document.body.append(div1);
+      document.body.append(div2);
     }
 
     var expectation = ShadowRoot.supported ? returnsNormally : throws;
 
     test("Shadowed nodes aren't visible to queries from outside ShadowDOM", () {
       expect(() {
         init();
 
         expect(queryAll('.foo'), equals([div1, paragraph2]));
       }, expectation);
@@ skipping 15 matching lines @@
 
     test('Querying in shadowed fragment respects the shadow boundary.', () {
       expect(() {
         init();
 
         expect(shadowRoot.queryAll('.foo'), equals([paragraph1]));
       }, expectation);
     });
   });
 }