Update platform_app.js to work even if window.history is not replaceable

chrome/renderer/resources/extensions/platform_app.js

 // Copyright (c) 2012 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.
 
 var $console = window.console;
 
 /**
  * Returns a function that logs a 'not available' error to the console and
  * returns undefined.
  *
@@ skipping 134 matching lines @@
   });
 }
 
 // Disable benign Document methods.
 disableMethods(HTMLDocument.prototype, 'document', ['open', 'clear', 'close']);
 
 // Replace evil Document methods with exception-throwing stubs.
 disableMethods(HTMLDocument.prototype, 'document', ['write', 'writeln'], true);
 
 // Disable history.
-window.history = {};
+Object.defineProperty(window, "history", { value: {} });
 disableGetters(window.history, 'history', ['back', 'forward', 'go', 'length']);
 
 // Disable find.
 disableMethods(Window.prototype, 'window', ['find']);
 
 // Disable modal dialogs. Shell windows disable these anyway, but it's nice to
 // warn.
 disableMethods(Window.prototype, 'window', ['alert', 'confirm', 'prompt']);
 
 // Disable window.*bar.
@@ skipping 32 matching lines @@
 
 // Disable onunload, onbeforeunload.
 disableSetters(Window.prototype, 'window', ['onbeforeunload', 'onunload']);
 var windowAddEventListener = Window.prototype.addEventListener;
 Window.prototype.addEventListener = function(type) {
   if (type === 'unload' || type === 'beforeunload')
     generateDisabledMethodStub(type)();
   else
     return $Function.apply(windowAddEventListener, window, arguments);
 };