big update to observe, template_binding, polymer

samples/third_party/todomvc/test/utils.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.utils;
 
 import 'dart:async';
 import 'package:observe/observe.dart';
 
 Future onPropertyInit(Observable obj, String path) {
   final obs = new PathObserver(obj, path);
   if (obs.value != null) return new Future.value(obs.value);
 
   final c = new Completer();
-  StreamSubscription sub;
-  sub = obs.changes.listen((_) {
-    if (obs.value != null) {
-      sub.cancel();
-      c.complete(obs.value);
+  obs.open((value) {
+    if (value != null) {
+      obs.close();
+      c.complete(value);
     }
   });
   return c.future;
 }