Converting Polymer's WebComponentsLoaded to an onReady future

samples/third_party/todomvc/test/mainpage_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 todomvc.test.mainpage_test;
 
-import 'dart:async';
 import 'dart:html';
+import 'package:polymer/polymer.dart';
+import 'package:unittest/html_config.dart';
 import 'package:unittest/unittest.dart';
-import 'package:unittest/html_config.dart';
 import '../web/app.dart';
 import '../web/model.dart';
 
 /**
  * This test runs the TodoMVC app and checks the state of the initial page.
  */
 // TODO(jmesserly): verify some styles (colors, fonts, relative size) as well.
 main() {
   useHtmlConfiguration();
 
-  setUp(() => new Future.delayed(Duration.ZERO));
+  setUp(() => Polymer.onReady);
 
   test('initial state', () {
     final todoApp = query('todo-app');
     expect(appModel.todos.length, 0);
-    expect(todoApp.xtag is TodoApp, true, reason: 'TodoApp should bee created');
+    expect(todoApp.xtag is TodoApp, true, reason: 'TodoApp should be created');
 
     final root = todoApp.shadowRoot;
     final newTodo = root.query('#new-todo');
     expect(newTodo.placeholder, "What needs to be done?");
 
     // TODO(jmesserly): re-enable this. It fails on Firefox with ShadowDOM.
     // The issue appears to be that
     // Wait for setTimeout 0 for focus to activate.
     /*Timer.run(expectAsync0(() {
       expect(document.activeElement, todoApp, reason: 'app should have focus');
       expect(root.activeElement, newTodo, reason: 'New todo should have focus');
       expect(root.queryAll('[is=todo-row]').length, 0, reason: 'no items yet');
     }));*/
   });
 }