use .append instead of .nodes.add

tests/html/dart_object_local_storage_test.dart

 library DartObjectLocalStorageTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
 import 'dart:html';
 
 // TODO(vsm): Rename this to wrapper_caching_test or similar.  It's
 // basically a port of dom/dart_object_local_storage_test.dart.  For
 // wrapping implementation of dart:html (i.e., the dartium one), it is
 // effectively testing dart_object_local_storage in the underlying dom
 // object.
 main() {
   useHtmlConfiguration();
 
   BodyElement body = document.body;
   Storage localStorage = window.localStorage;
   Storage sessionStorage = window.sessionStorage;
   var element = new Element.tag('canvas');
   element.id = 'test';
-  body.nodes.add(element);
+  body.append(element);
 
   test('body', () {
       expect(body, equals(document.body));
   });
   test('localStorage', () {
       expect(localStorage, equals(window.localStorage));
   });
   test('sessionStorage', () {
       expect(sessionStorage, equals(window.sessionStorage));
   });
   test('unknown', () {
       var test = document.query('#test');
       expect(element, equals(test));
   });
 }