Retain a registration that has a non-null newest worker in Handle Service Worker Client Unload.
Retain a registration that has a non-null newest worker in Handle Service Worker Client Unload.

martinthomson/ServiceWorker,slightlyoff/ServiceWorker,mkruisselbrink/ServiceWorker,martinthomson/ServiceWorker,mkruisselbrink/ServiceWorker,martinthomson/ServiceWorker,slightlyoff/ServiceWorker