fix #136, support watch exprs and two way bindings for component fields

lib/web_components.dart

 // Copyright (c) 2012, 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.
 
 /**
  * This library exposes the types in [watcher], [safe_html], [templating] and
  * the [WebComponent] base class. See this article for more information about
  * this library: <http://www.dartlang.org/articles/dart-web-components/>.
  */
 library web_components;
@@ skipping 248 matching lines @@
   static void _distribute(Element insertionPoint, List<Node> nodes) {
     assert(_isInsertionPoint(insertionPoint));
     for (var node in nodes) {
       insertionPoint.parent.insertBefore(node, insertionPoint);
     }
     insertionPoint.remove();
   }
 
   // TODO(jmesserly): this forwarding is temporary until Dart supports
   // subclassing Elements.
+  // TODO(jmesserly): we were missing the setter for title, are other things
+  // missing setters?
 
   List<Node> get nodes => _element.nodes;
 
   set nodes(Collection<Node> value) { _element.nodes = value; }
 
   /**
    * Replaces this node with another node.
    */
   Node replaceWith(Node otherNode) { _element.replaceWith(otherNode); }
 
@@ skipping 75 matching lines @@
   String get lang => _element.lang;
 
   String get outerHTML => _element.outerHTML;
 
   bool get spellcheck => _element.spellcheck;
 
   int get tabIndex => _element.tabIndex;
 
   String get title => _element.title;
 
+  set title(String value) { _element.title = value; }
+
   bool get translate => _element.translate;
 
   String get webkitdropzone => _element.webkitdropzone;
 
   void click() { _element.click(); }
 
   Element insertAdjacentElement(String where, Element element) =>
     _element.insertAdjacentElement(where, element);
 
   void insertAdjacentHTML(String where, String html) {
@@ skipping 162 matching lines @@
 }
 
 /**
  * Set this to true to use native Shadow DOM if it is supported.
  * Note that this will change behavior of [WebComponent] APIs for tree
  * traversal.
  */
 bool useShadowDom = false;
 
 bool get _realShadowRoot => useShadowDom && ShadowRoot.supported;