Introduce boot.js: this finally makes it possible to load and run Todomvc

example/todomvc/web/router_options.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 router_options;
 
 import 'dart:html';
 import 'package:polymer/polymer.dart';
 
 /**
  * Given a set of child links to this page, this will add the "selected" CSS
  * class to the link that matches window.location.hash.
  *
  * For example, if the current window.location.hash is "#/completed" and we
  * have a tag like `<a href="#/completed">` it will get the class
  * `class="selected"`, and other links will have that CSS class removed.
  */
+@CustomTag('router-options')
 class RouterOptions extends PolymerElement {
 
   bool get applyAuthorStyles => true;
   var _sub;
 
   void inserted() {
     super.inserted();
 
     var anchors = this.queryAll('a');
 
@@ skipping 11 matching lines @@
 
     _updateHash(null);
     _sub = windowLocation.changes.listen(_updateHash);
   }
 
   void removed() {
     _sub.cancel();
     super.removed();
   }
 }