[ServiceWorker] Update formatting for tests.

LayoutTests/http/tests/serviceworker/resources/events-worker.js

 var eventsSeen = [];
 
 function handler(event) { eventsSeen.push(event.type); }
 
 ['activate', 'install'].forEach(function(type) {
     self.addEventListener(type, handler);
-});
+  });
 
 onmessage = function(e) {
-    var message = e.data;
-    message.port.postMessage({events: eventsSeen});
+  var message = e.data;
+  message.port.postMessage({events: eventsSeen});
 };