[DevTools] Prepare to pass modified InspectorFrontendHost to inspector app.

Source/devtools/front_end/host/InspectorAppHost.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
- */
-function InspectorAppHostAPI()
-{
-}
-
-InspectorAppHostAPI.prototype = {
-    /**
-     * @param {!Window} window
-     */
-    inspectorAppWindowLoaded: function(window) { },
-
-    beforeInspectorAppLoad: function() { },
-
-    afterInspectorAppLoad: function() { }
-}
-
-/**
- * @type {!InspectorAppHostAPI}
- */
-var InspectorAppHost;
-
-/**
- * @suppressGlobalPropertiesCheck
- */
-(function()
-{
-    if (window.parent !== window) {
-        InspectorAppHost = window.parent.InspectorAppHost;
-        InspectorAppHost.inspectorAppWindowLoaded(window);
-    }
-})();