[ServiceWorker] Update formatting for tests.

LayoutTests/http/tests/serviceworker/resources/onactivate-throw-error-from-nested-event-worker.js

 var max_nesting_level = 8;
 
 self.addEventListener('message', function(event) {
     var level = event.data;
     if (level < max_nesting_level)
-        dispatchEvent(new MessageEvent('message', { data: level + 1 }));
+      dispatchEvent(new MessageEvent('message', { data: level + 1 }));
     throw Error('error at level ' + level);
   });
 
 self.addEventListener('activate', function(event) {
     dispatchEvent(new MessageEvent('message', { data: 1 }));
   });