ServiceWorker: Add support for .skipWaiting and controllerchange event(1/3)

LayoutTests/http/tests/serviceworker/resources/test-helpers.js

 // Adapter for testharness.js-style tests with Service Workers
 
 function service_worker_unregister_and_register(test, url, scope) {
   if (!scope || scope.length == 0)
     return Promise.reject(new Error('tests must define a scope'));
 
   var options = { scope: scope };
   return service_worker_unregister(test, scope)
     .then(function() {
         return navigator.serviceWorker.register(url, options);
@@ skipping 198 matching lines @@
           registration = r;
           return wait_for_update(test, registration);
         })
       .then(function(worker) { return fetch_tests_from_worker(worker); })
       .then(function() { return registration.unregister(); })
       .then(function() { test.done(); })
       .catch(test.step_func(function(e) { throw e; }));
   };
 
   self.service_worker_test = service_worker_test;
+  self.fetch_tests_from_worker = fetch_tests_from_worker;
 })();
 
 function get_host_info() {
   var ORIGINAL_HOST = '127.0.0.1';
   var REMOTE_HOST = 'localhost';
   var UNAUTHENTICATED_HOST = 'example.test';
   var HTTP_PORT = 8000;
   var HTTPS_PORT = 8443;
   try {
     // In W3C test, we can get the hostname and port number in config.json
@@ skipping 28 matching lines @@
             channel.port1.onmessage = test.step_func(function() {
                 unload_iframe(frame).catch(function() {});
                 resolve();
               });
             frame.contentWindow.postMessage(
               {username: username, password: password, cookie: cookie},
               [channel.port2], origin);
           }));
     });
 }