Port of github.com/polymer/polymer.

pkg/observe/lib/src/bind_property.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.
 
 part of observe;
 
 /**
  * Forwards an observable property from one object to another. For example:
  *
  *     class MyModel extends ObservableBase {
  *       StreamSubscription _sub;
  *       MyOtherModel _otherModel;
  *
  *       MyModel() {
  *         ...
- *         _sub = bindProperty(_otherModel, const Symbol('value'),
+ *         _sub = onPropertyChange(_otherModel, const Symbol('value'),
  *             () => notifyProperty(this, const Symbol('prop'));
  *       }
  *
  *       String get prop => _otherModel.value;
  *       set prop(String value) { _otherModel.value = value; }
  *     }
  *
  * See also [notifyProperty].
  */
-StreamSubscription bindProperty(Observable source, Symbol sourceName,
+// TODO(jmesserly): make this an instance method?
+StreamSubscription onPropertyChange(Observable source, Symbol sourceName,
     void callback()) {
   return source.changes.listen((records) {
     for (var record in records) {
       if (record.changes(sourceName)) {
         callback();
       }
     }
   });
 }