[DevTools] Make toolbar counters declarative.

Source/devtools/front_end/main/App.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @constructor
  * @implements {WebInspector.Console.UIDelegate}
  */
 WebInspector.App = function()
 {
@@ skipping 47 matching lines @@
     },
 
     showConsole: function()
     {
         WebInspector.Revealer.reveal(WebInspector.console);
     }
 };
 
 /**
  * @constructor
- * @implements {WebInspector.StatusBarButton.Provider}
+ * @implements {WebInspector.StatusBarItem.Provider}
  */
 WebInspector.App.EmulationButtonProvider = function()
 {
 }
 
 WebInspector.App.EmulationButtonProvider.prototype = {
     /**
-     * @return {?WebInspector.StatusBarButton}
+     * @return {?WebInspector.StatusBarItem}
      */
-    button: function()
+    item: function()
     {
         if (!(WebInspector.app instanceof WebInspector.App))
             return null;
         return WebInspector.app._toggleEmulationButton || null;
     }
 }
 
 /**
  * @type {!WebInspector.App}
  */
 WebInspector.app;