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

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

 // Copyright (c) 2011 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() {
   chrome.contextMenus.create(
       {"title":"Page item", contexts: ["page"]},
       function() {
-        if (!chrome.extension.lastError) {
+        if (!chrome.runtime.lastError) {
           chrome.contextMenus.create(
           {"title":"Frame item", contexts: ["frame"]},
           function() {
-            if (!chrome.extension.lastError) {
+            if (!chrome.runtime.lastError) {
               chrome.test.sendMessage("created items");
             }
           });
         }
       });
 };