[DropdownMenu][ContextMenu] Prevent text selection on menu close in Firefox

[jjenzz]

Hopefully the code comments explain clearly what is going on here 🤞

Fixes #742.

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UPDATE: The original change I made here was no longer needed as the changes I made to fix Dialog.Trigger / DropdownMenu.Item composition also fixed this.

I've updated the code comments to explain that it covers this case too and the explanation as to why it fixes this is as follows:

Browsers wait for our handler logic to execute before executing their own implementation in case we have prevented their default behaviour. Therefore, the menu will unmount before the browser's pointerup logic has executed causing pointerdown to be stuck in some browsers. In FF this resulted in text selection occurring on the page when moving the mouse after close. We move the unmount logic till after the browser receives the pointerup to avoid this.

[andy-hook]

I remember exploring a similar approach for fixing #634 but abandoned because we discussed doing something with event composition instead.

I've just tested that issue and it does indeed fix it as well 👍 this raises the question of whether we're ok introducing this timer, I'm personally fine with it for now given the absence of an alternative approach.

Do we see any unexpected issues resulting from the timer though?

[nvie]

Amazing, thanks for the fix!