Added helper function to automatically dirty a RenderingScheduler on attribute change

runtime/observatory/lib/src/elements/nav/refresh.dart

 // Copyright (c) 2016, 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.
 
 import 'dart:html';
 import 'dart:async';
 import 'package:observatory/src/elements/helpers/tag.dart';
 import 'package:observatory/src/elements/helpers/rendering_scheduler.dart';
 
 class RefreshEvent {
   final NavRefreshElement element;
   RefreshEvent(this.element);
 }
 
 class NavRefreshElement extends HtmlElement implements Renderable {
   static const tag = const Tag<NavRefreshElement>('nav-refresh-wrapped');
 
   RenderingScheduler _r;
 
   Stream<RenderedEvent<NavRefreshElement>> get onRendered => _r.onRendered;
 
   final StreamController<RefreshEvent> _onRefresh =
                                 new StreamController<RefreshEvent>.broadcast();
   Stream<RefreshEvent> get onRefresh => _onRefresh.stream;
 
   bool _disabled;
   String _label;
   bool get disabled => _disabled;
   String get label => _label;
-  set disabled(bool value) {
-    if (_disabled != value) {
-      _disabled = value;
-      _r.dirty();
-    } else {
-      _r.scheduleNotification();
-    }
-  }
-  set label(String value) {
-    if (_label != value) {
-      _label = value;
-      _r.dirty();
-    } else {
-      _r.scheduleNotification();
-    }
-  }
-
+  set disabled(bool value) => _disabled = _r.checkAndReact(_disabled, value);
+  set label(String value) => _label = _r.checkAndReact(_label, value);
 
   factory NavRefreshElement({String label: 'Refresh', bool disabled: false,
                              RenderingQueue queue}) {
     assert(label != null);
     assert(disabled != null);
     NavRefreshElement e = document.createElement(tag.name);
     e._r = new RenderingScheduler(e, queue: queue);
     e._label = label;
     e._disabled = disabled;
     return e;
@@ skipping 26 matching lines @@
   void _refresh(RefreshEvent e) {
     if (_disabled) return;
     _onRefresh.add(e);
   }
 
   void refresh() {
     if (_disabled) return;
     _refresh(new RefreshEvent(this));
   }
 }