Update references to the extension messaging APIs to point to the "runtime"

chrome/test/data/extensions/context_menus/long_title/test.js

 // Copyright (c) 2010 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.
 
 window.onload = function() {
   // Make a 1000-character long title.
   var title = "";
   for (var i = 0; i < 1000; i++) {
     title += "x";
   }
   chrome.test.log("creating item");
   chrome.contextMenus.create({"title":title}, function() {
-    if (!chrome.extension.lastError) {
+    if (!chrome.runtime.lastError) {
       chrome.test.sendMessage("created");
     }
   });
 };