[DevTools] Make toolbar counters declarative.

Source/devtools/front_end/main/ScreencastApp.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
  * @extends {WebInspector.App}
  */
 WebInspector.ScreencastApp = function()
 {
@@ skipping 60 matching lines @@
         this._rootSplitView.toggleResizer(this._rootSplitView.resizerElement(), true);
         this._rootSplitView.toggleResizer(WebInspector.inspectorView.topResizerElement(), state === "top");
         this._rootSplitView.showBoth();
     },
 
     __proto__: WebInspector.App.prototype
 };
 
 /**
  * @constructor
- * @implements {WebInspector.StatusBarButton.Provider}
+ * @implements {WebInspector.StatusBarItem.Provider}
  */
 WebInspector.ScreencastApp.StatusBarButtonProvider = function()
 {
 }
 
 WebInspector.ScreencastApp.StatusBarButtonProvider.prototype = {
     /**
-     * @return {?WebInspector.StatusBarButton}
+     * @return {?WebInspector.StatusBarItem}
      */
-    button: function()
+    item: function()
     {
         if (!(WebInspector.app instanceof WebInspector.ScreencastApp))
             return null;
         return /** @type {!WebInspector.ScreencastApp} */ (WebInspector.app)._toggleScreencastButton;
     }
 }