[DevTools] Extract part of DevTools into inspector app.

Source/devtools/front_end/toolbox_bootstrap/Toolbox.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.
 
 // FIXME: This stub is invoked from the backend and should be removed
 // once we migrate to the "pull" model for extensions retrieval.
 WebInspector = {};
 WebInspector.addExtensions = function() {};
 
 (function()
 {
 
 /**
  * @suppressGlobalPropertiesCheck
  */
 function toolboxLoaded()
 {
     if (!window.opener)
         return;
     window.opener.WebInspector["app"]["toolboxLoaded"](document);
 }
 
-/**
- * @suppressGlobalPropertiesCheck
- */
-function windowLoaded()
-{
-    window.removeEventListener("DOMContentLoaded", windowLoaded, false);
-    toolboxLoaded();
-}
-
-/**
- * @suppressGlobalPropertiesCheck
- */
-function initToolbox()
-{
-    if (document.readyState === "complete")
-        toolboxLoaded();
-    else
-        window.addEventListener("DOMContentLoaded", windowLoaded, false);
-}
-initToolbox();
+runOnWindowLoad(toolboxLoaded);
 
 })();