use .append instead of .nodes.add

tests/html/datalistelement_test.dart

 // Copyright (c) 2012, 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 datalistelement_dataview_test;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
 import 'dart:html';
 
 main() {
   useHtmlConfiguration();
 
   var isDataListElement =
       predicate((x) => x is DataListElement, 'is a DataListElement');
 
   var div;
 
   setUp(() {
       div = new DivElement();
-      document.body.nodes.add(div);
+      document.body.append(div);
       div.innerHtml = """
 <input id="input" list="browsers" />
 <datalist id="browsers">
   <option value="Chrome">
   <option value="Firefox">
   <option value="Internet Explorer">
   <option value="Opera">
   <option value="Safari">
 </datalist>
 """;
@@ skipping 29 matching lines @@
     }, expectation);
   });
 
   test('create', () {
     expect(() {
       var list = new DataListElement();
       expect(list, isDataListElement);
     }, expectation);
   });
 }