Service Worker: Add tests for same-scope new script registration

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

 // Adapter for testharness.js-style tests with Service Workers
 
 // Can only be used with a worker that installs successfully, since it
 // first registers to acquire a ServiceWorkerRegistration object to
 // unregister.
 // FIXME: Use getRegistration() when implemented.
 function service_worker_unregister_and_register(test, url, scope) {
   if (!scope || scope.length == 0)
     return Promise.reject(new Error('tests must define a scope'));
 
@@ skipping 48 matching lines @@
   iframe.src = '';
   iframe.remove();
   return saw_unload;
 }
 
 function normalizeURL(url) {
   return new URL(url, document.location).toString().replace(/#.*$/, '');
 }
 
 function wait_for_update(test, registration) {
-    return new Promise(test.step_func(function(resolve) {
-        registration.addEventListener('updatefound', test.step_func(function() {
-            resolve(registration.installing);
-        }));
+  if (!registration || registration.unregister == undefined) {
+    return Promise.reject(new Error(
+      'wait_for_update must be passed a ServiceWorkerRegistration'));
+  }
+
+  return new Promise(test.step_func(function(resolve) {
+      registration.addEventListener('updatefound', test.step_func(function() {
+          resolve(registration.installing);
+      }));
     }));
 }
 
 function wait_for_state(test, worker, state) {
-    return new Promise(test.step_func(function(resolve) {
-        worker.addEventListener('statechange', test.step_func(function() {
-            if (worker.state === state)
-                resolve(state);
+  if (!worker || worker.state == undefined) {
+    return Promise.reject(new Error(
+      'wait_for_state must be passed a ServiceWorker'));
+  }
+
+  return new Promise(test.step_func(function(resolve) {
+      worker.addEventListener('statechange', test.step_func(function() {
+          if (worker.state === state)
+            resolve(state);
         }));
     }));
 }
 
 (function() {
   function fetch_tests_from_worker(worker) {
     return new Promise(function(resolve, reject) {
         var messageChannel = new MessageChannel();
         messageChannel.port1.addEventListener('message', function(message) {
             if (message.data.type == 'complete') {
@@ skipping 66 matching lines @@
         HTTP_ORIGIN: 'http://' + ORIGINAL_HOST + ':' + HTTP_PORT,
         HTTPS_ORIGIN: 'https://' + ORIGINAL_HOST + ':' + HTTPS_PORT,
         HTTP_REMOTE_ORIGIN: 'http://' + REMOTE_HOST + ':' + HTTP_PORT,
         HTTPS_REMOTE_ORIGIN: 'https://' + REMOTE_HOST + ':' + HTTPS_PORT
     };
 }
 
 function base_path() {
     return location.pathname.replace(/\/[^\/]*$/, '/');
 }