[ServiceWorker] Should skipWaiting() wait for an "in-progress request" to finish? (#569)

The Activate algorithm blocks on "in-progress requests":
> If exitingWorker is not null, then:
> Wait for exitingWorker to finish handling any in-progress requests.

What is the definition of an "in-progress request"? Does this mean skipWaiting() will fail to upgrade if you have a buggy SW like:
```javascript
onfetch = function(e) { e.respondWith(new Promise(){}); };
```
That wouldn't work for a use case of skipWaiting() to act as a kill-switch for bad SW.

---
Reply to this email directly or view it on GitHub:
https://github.com/slightlyoff/ServiceWorker/issues/569