Describe waitUntil() behavior in terms of Promise.all()

[nikhilm]

It seems to me like waitUntil() can be significantly simplified if it uses Promise.all that is now in the ES spec.

While the event is dispatching (since waitUntil() can't be called when async), every promise passed to it is appended to an array. At the end of the dispatch wait on Promise.all(list of promises). That way we get 'rejection gets priority' for free.

[nikhilm]

The callsites at [[Install]] and [[Activate]] are sort of updated, but the description of waitUntil() could use some cleaning up.

[jungkees]

We're already using Promise.all() for waitUntil().

While the event is dispatching (since waitUntil() can't be called when async), every promise passed to it is appended to an array.

event object's extend lifetime promises is an array of promises to keep the list of the added promises.

At the end of the dispatch wait on Promise.all(list of promises). That way we get 'rejection gets priority' for free.

The task that runs the waitUntil() is actually doing this: "waiting for all of extendLifetimePromises settles."

It's sort of double-defined once in waitUntil()'s task algorithm's step 3 and Install algorithm step 11.5 and Active algorithm step 15.5.

May be we can try to simplify this bit by reducing one side of such steps, but on one hand I think it seems easier to understand the relationship of those algorithms as-is.

And waiting for all of, the algorithm description for Promise.all, is already giving us 'rejection gets priority' semantic as you pointed.

[jakearchibald]

Closing in favour of #771