DevTools: only allow status bar items in status bars.

Source/devtools/front_end/extensions/ExtensionServer.js

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 276 matching lines @@
         var button = new WebInspector.ExtensionButton(this, message.id, this._expandResourcePath(port._extensionOrigin, message.icon), message.tooltip, message.disabled);
         this._clientObjects[message.id] = button;
 
         panelDescriptor.panel().then(appendButton).done();
 
         /**
          * @param {!WebInspector.Panel} panel
          */
         function appendButton(panel)
         {
-            /** @type {!WebInspector.ExtensionPanel} panel*/ (panel).addStatusBarItem(button.element);
+            /** @type {!WebInspector.ExtensionPanel} panel*/ (panel).addStatusBarItem(button.statusBarButton());
         }
 
         return this._status.OK();
     },
 
     _onUpdateButton: function(message, port)
     {
         var button = this._clientObjects[message.id];
         if (!button || !(button instanceof WebInspector.ExtensionButton))
             return this._status.E_NOTFOUND(message.id);
@@ skipping 816 matching lines @@
     this.E_FAILED = makeStatus.bind(null, "E_FAILED", "Operation failed: %s");
 }
 
 /**
  * @typedef {{code: string, description: string, details: !Array.<*>}}
  */
 WebInspector.ExtensionStatus.Record;
 
 WebInspector.extensionAPI = {};
 defineCommonExtensionSymbols(WebInspector.extensionAPI);