use .append instead of .nodes.add

tests/html/node_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 node_bindings_test;
 
 import 'dart:async';
 import 'dart:html';
 import 'package:mdv_observe/mdv_observe.dart';
 import 'package:unittest/html_config.dart';
 import 'package:unittest/unittest.dart';
 import 'mdv_observe_utils.dart';
 
 // Note: this file ported from
 // https://github.com/toolkitchen/mdv/blob/master/tests/node_bindings.js
 
 main() {
   useHtmlConfiguration();
   group('Node Bindings', nodeBindingTests);
 }
 
 sym(x) => new Symbol(x);
 
 nodeBindingTests() {
   var testDiv;
 
   setUp(() {
-    document.body.nodes.add(testDiv = new DivElement());
+    document.body.append(testDiv = new DivElement());
   });
 
   tearDown(() {
     testDiv.remove();
     testDiv = null;
   });
 
   dispatchEvent(type, target) {
     target.dispatchEvent(new Event(type, cancelable: false));
   }
@@ skipping 89 matching lines @@
     input.unbind('checked');
 
     input.checked = false;
     dispatchEvent('change', input);
     expect(model[sym('x')], true,
         reason: 'disconnected binding should not fire');
   });
 
   test('Checkbox Input', () {
     var input = new InputElement();
-    testDiv.nodes.add(input);
+    testDiv.append(input);
     input.type = 'checkbox';
     var model = toSymbolMap({'x': true});
     input.bind('checked', model, 'x');
     expect(input.checked, true);
 
     model[sym('x')] = false;
     expect(input.checked, true, reason: 'changes delivered async');
     deliverChangeRecords();
     expect(input.checked, false);
 
     input.click();
     expect(model[sym('x')], true);
     deliverChangeRecords();
 
     input.click();
     expect(model[sym('x')], false);
   });
 }