Implement ServiceWorkerClient attributes [3/3]

LayoutTests/http/tests/serviceworker/clients-getall.html

+<!DOCTYPE html>
+<title>Service Worker: ServiceWorkerClient.getAll</title>
+<script src="../resources/testharness.js"></script>
+<script src="../resources/testharnessreport.js"></script>
+<script src="resources/test-helpers.js"></script>
+<script>
+var scope = 'resources/blank.html?clients-getAll';
+var t = async_test('Test ServiceWorkerClient.getAll()');
+t.step(function() {
+    service_worker_unregister_and_register(
+        t, 'resources/clients-getall-worker.js', scope)
+      .then(function(registration) {
+          return wait_for_state(t, registration.installing, 'activated');
+        })
+      .then(function() { return with_iframe(scope + '#1'); })
+      .then(function(frame1) {
+          frame1.focus();
+          return with_iframe(scope + '#2');
+        })
+      .then(function(frame2) {
+          var channel = new MessageChannel();
+          channel.port1.onmessage = t.step_func(onMessage);
+          frame2.contentWindow.navigator.serviceWorker.controller.postMessage(
+              {port:channel.port2}, [channel.port2]);
+        })
+      .catch(unreached_rejection(t));
+  });
+
+var expected = [
+    /* visibilityState, focused, url, frameType */
+    ['visible', true, new URL(scope + '#1', location).toString(), 'nested'],
+    ['visible', false, new URL(scope + '#2', location).toString(), 'nested']
+];
+
+function onMessage(e) {
+  assert_equals(e.data.length, 2);
+  assert_array_equals(e.data[0], expected[0]);
+  assert_array_equals(e.data[1], expected[1]);
+  service_worker_unregister_and_done(t, scope);
+}
+</script>