Re: [ServiceWorker] Promise on navigator.serviceWorker that resolves when page is controlled (#799)

If `.ready` were designed to resolve when the client got a controller, we couldn't use it for the initial client loading triggered w/o a registration and the shift + reload case (as that client will live w/o a controller for its lifetime). `controllerchange` is exactly the event to catch the client's controller (active worker) change.

I think changing the behavior of `.ready` is not a good idea. Let's discuss whether we really want to add such an API.

/cc @jakearchibald @slightlyoff 

---
Reply to this email directly or view it on GitHub:
https://github.com/slightlyoff/ServiceWorker/issues/799#issuecomment-164393241