Update TodoMVC based on https://github.com/polymer/todomvc

samples/third_party/todomvc/web/todo_row.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.web.todo_row;
-
-import 'dart:html';
-import 'package:polymer/polymer.dart';
-import 'model.dart';
-
-@CustomTag('todo-row')
-class TodoRow extends LIElement with Polymer, Observable {
-  @published Todo todo;
-
-  bool get applyAuthorStyles => true;
-
-  factory TodoRow() => new Element.tag('todo-row');
-
-  TodoRow.created() : super.created() {
-    polymerCreated();
-  }
-
-  void ready() {
-    var root = getShadowRoot("todo-row");
-    var label = root.querySelector('#label');
-    var item = root.querySelector('.todo-item');
-
-    bindCssClass(item, 'completed', this, 'todo.done');
-    bindCssClass(item, 'editing', label, 'editing');
-  }
-
-  void removeTodo() { appModel.todos.remove(todo); }
-}