[ServiceWorker] Tests for WindowClient.focus().

LayoutTests/http/tests/serviceworker/chromium/resources/notificationclick-can-focus.js

 // This helper will setup a small test framework that will use TESTS and run
-// them iteratively and call self.postMessage('quit') when done.
+// them sequentially and call self.postMessage('quit') when done.
 // This helper also exposes |client|, |postMessage()|, |runNextTestOrQuit()|,
 // |synthesizeNotificationClick()| and |initialize()|.
 importScripts('sw-test-helpers.js');
 
 var TESTS = [
     function testWithNoNotificationClick() {
         client.focus().catch(function() {
             self.postMessage('focus() outside of a notificationclick event failed');
         }).then(runNextTestOrQuit);
     },
@@ skipping 59 matching lines @@
             e.waitUntil(clients.openWindow('/foo.html').then(function() {
                 client.focus().catch(function() {
                     self.postMessage('focus() failed because a window was opened before');
                 }).then(runNextTestOrQuit);
             }));
         });
     },
 ];
 
 self.onmessage = function(e) {
-    if (e.data == "start") {
+    if (e.data == 'start') {
         initialize().then(runNextTestOrQuit);
     } else {
         initialize().then(function() {
             self.postMessage('received unexpected message');
             self.postMessage('quit');
         });
     }
-}
+};