Centralized event streams

runtime/observatory/lib/src/elements/nav/library_menu.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/models.dart' as M show IsolateRef, LibraryRef;
 import 'package:observatory/src/elements/helpers/rendering_scheduler.dart';
 import 'package:observatory/src/elements/helpers/tag.dart';
 import 'package:observatory/src/elements/helpers/uris.dart';
 import 'package:observatory/src/elements/nav/menu.dart';
 
 class NavLibraryMenuElement extends HtmlElement implements Renderable {
   static const tag = const Tag<NavLibraryMenuElement>('nav-library-menu',
                      dependencies: const [NavMenuElement.tag]);
 
   RenderingScheduler _r;
 
   Stream<RenderedEvent<NavLibraryMenuElement>> get onRendered => _r.onRendered;
 
   bool _last;
   M.IsolateRef _isolate;
   M.LibraryRef _library;
+
   bool get last => _last;
   M.IsolateRef get isolate => _isolate;
   M.LibraryRef get library => _library;
+  
   set last(bool value) => _last = _r.checkAndReact(_last, value);
 
   factory NavLibraryMenuElement(M.IsolateRef isolate, M.LibraryRef library,
       {bool last: false, RenderingQueue queue}) {
     assert(isolate != null);
     assert(library != null);
     assert(last != null);
     NavLibraryMenuElement e = document.createElement(tag.name);
     e._r = new RenderingScheduler(e, queue: queue);
     e._isolate = isolate;
     e._library = library;
     e._last = last;
     return e;
   }
 
   NavLibraryMenuElement.created() : super.created() { createShadowRoot(); }
 
   @override
-  void attached() { super.attached(); _r.enable(); }
+  void attached() {
+    super.attached();
+    _r.enable();
+  }
 
   @override
   void detached() {
-    super.detached(); _r.disable(notify: true);
+    super.detached();
+    _r.disable(notify: true);
     shadowRoot.children = [];
   }
 
   void render() {
     shadowRoot.children = [
       new NavMenuElement(library.name, last: last, queue: _r.queue,
                 link: Uris.inspect(isolate, object: library).toString())
         ..children = [new ContentElement()]
     ];
   }
 }