Normative: Use onFinally's realm when creating functions in Promise.prototype.finally (fixes #2222)

[arai-a]

Changed Promise.prototype.finally to use onFinally's realm when creating thenFinally and catchFinally,
so that embedding uses onFinally's realm's global when checking if job's global is fully active.

This fixes #2222

[ljharb]

Does this need consensus, and/or does it match what engines already do? My assumption is yes and yes.

[arai-a]

test is in tc39/test262#2910.
According to the result there, most engines follow current spec (create thenFinally and catchFinally in finally method's realm) and don't match to the modified behavior.
As described in issue #2222, this mostly affects only embedding scenario, and this is normative change for consistency.

I don't know about consensus requirement, but would be nice to get feedback from devs?

[ljharb]

Seems best to discuss it in the next plenary.

The “has tests” label will be applied when the tests PR is merged, after it has consensus.

[ljharb]

I've added this to the agenda for next month's meeting.

[ljharb]

This was discussed (1 2).

Conclusion was that @codehag would update the PR/issue to refer to Mozilla's bug, and for @codehag, @erights, and myself to discuss further, which we have not yet done.

[codehag]

Thanks for the reminder, I will find some time for this before the next meeting.

[ljharb]

ping @codehag @dminor, it'd be great to get this moving forward, if it's still important.

[codehag]

We still want to do this. I just need to refresh my memory on it, thanks again for ping.

[ljharb]

@dminor any update from spidermonkey on this one?