Update IDL for ServiceWorker interface and ServiceWorkerContainer interface per F2F discussion.
Update IDL for ServiceWorker interface and ServiceWorkerContainer interface per F2F discussion.

martinthomson/ServiceWorker,zuzusik/ServiceWorker,mkruisselbrink/ServiceWorker,slightlyoff/ServiceWorker,justinleoye/ServiceWorker,zuzusik/ServiceWorker,karolklp/ServiceWorker,mkruisselbrink/ServiceWorker,justinleoye/ServiceWorker,karolklp/ServiceWorker,martinthomson/ServiceWorker,justinleoye/ServiceWorker,chadoliver/ServiceWorker,martinthomson/ServiceWorker,karolklp/ServiceWorker,chadoliver/ServiceWorker,chadoliver/ServiceWorker,zuzusik/ServiceWorker,slightlyoff/ServiceWorker