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';
 
 /**
@@ skipping 28 matching lines @@
 
     _updateHash(null);
     _sub = windowLocation.changes.listen(_updateHash);
   }
 
   void removed() {
     _sub.cancel();
     super.removed();
   }
 }
+
+_init() {
+  registerPolymerElement('router-options', () => new RouterOptions());
+}