Spin off of  issue 616331 

See comment #24 and #25:

Comment 24 by bkelly@mozilla.com, Aug 3
By the way, I found another issue related to this.  Its possible you already cover it, but I wanted to bring it to your attention.  I wrote it up on the spec issue:

https://github.com/slightlyoff/ServiceWorker/issues/916#issuecomment-237272060

Just cross posting here since I know github email can easily get lost.


Comment 25 by bkelly@mozilla.com, Aug 4
Another issue I ran into:

Do you delay activation if the current .active worker is still in the activating state?  For example, do you wait for the activate event to finish processing?

It seems like we must since we could potentially have functional events queued up to fire after the activate event finishes.