ServiceWorker: support Response.{status,statusText,headers} [blink] (2/3)

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

 // Adapter for testharness.js-style tests with Service Workers
 
 function service_worker_test(url, description) {
     var t = async_test(description);
     t.step(function() {
+        var scope = 'nonexistent';
+        service_worker_unregister_and_register(t, url, scope, onRegistered);
 
-        navigator.serviceWorker.register(url, {scope:'nonexistent'}).then(
-            t.step_func(function(worker) {
-                var messageChannel = new MessageChannel();
-                messageChannel.port1.onmessage = t.step_func(onMessage);
-                worker.postMessage({port:messageChannel.port2}, [messageChannel.port2]);
-            }),
-            unreached_rejection(t, 'Registration should succeed, but failed')
-        );
+        function onRegistered(worker) {
+            var messageChannel = new MessageChannel();
+            messageChannel.port1.onmessage = t.step_func(onMessage);
+            worker.postMessage({port:messageChannel.port2}, [messageChannel.port2]);
+        }
 
         function onMessage(e) {
             assert_equals(e.data, 'pass');
-            t.done();
+            service_worker_unregister_and_done(t, scope);
         }
     });
 }
 
 function service_worker_unregister_and_register(test, url, scope, onregister) {
     var options = scope ? { scope: scope } : {};
     return navigator.serviceWorker.unregister(scope).then(
         // FIXME: Wrap this with test.step_func once testharness.js is updated.
         function() {
             return navigator.serviceWorker.register(url, options);
@@ skipping 24 matching lines @@
   frame.src = url;
   frame.onload = function() {
       f(frame);
   };
   document.body.appendChild(frame);
 }
 
 function normalizeURL(url) {
   return new URL(url, document.location).toString().replace(/#.*$/, '');
 }