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

chrome/test/data/extensions/api_test/content_scripts/isolated_world1/background.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.
 
-chrome.extension.onConnect.addListener(function(port) {
+chrome.runtime.onConnect.addListener(function(port) {
   chrome.test.log("got connect");
   port.onMessage.addListener(function(msg) {
     chrome.test.log("got message: " + msg);
     chrome.test.assertEq(2, msg);
     chrome.test.notifyPass();
   });
 });
 
 chrome.tabs.onUpdated.addListener(function(tabId, changeInfo, tab) {
   chrome.test.log("Got update event: " + JSON.stringify(changeInfo));
   if (changeInfo.status == "complete") {
     chrome.tabs.executeScript(tabId, {file: "c.js"});
     chrome.tabs.onUpdated.removeListener(arguments.callee);
   }
 });
 
 chrome.test.getConfig(function(config) {
   chrome.test.log("Creating tab...");
   chrome.tabs.create({
     url: "http://localhost:PORT/files/extensions/test_file.html"
              .replace(/PORT/, config.testServer.port)
   });
 });