Revert of [DevTools] Inject element into toolbox window, do not load modules there.

Source/devtools/front_end/toolbox/ToolboxDelegate.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.
 
 /**
  * @interface
  */
 WebInspector.ToolboxDelegate = function() {}
 
 WebInspector.ToolboxDelegate.prototype = {
     /**
-     * @param {!Element} rootElement
+     * @param {!WebInspector.ResponsiveDesignView} responsiveDesignView
+     * @param {!WebInspector.InspectedPagePlaceholder} placeholder
      */
-    toolboxLoaded: function(rootElement) {},
-
-    /**
-     * @return {!InspectorFrontendHostAPI}
-     */
-    inspectorFrontendHost: function() {}
+    toolboxLoaded: function(responsiveDesignView, placeholder) {}
 }