[fullscreen] Ensure that requestFullscreen() and exitFullscreen() promise callbacks are run in time for animation frame (#16)

Issue to keep track of timing problem discussed in bug 27674 comments [#21](https://www.w3.org/Bugs/Public/show_bug.cgi?id=27674#c21)-[#31](https://www.w3.org/Bugs/Public/show_bug.cgi?id=27674#c31).

The overall integration with animation frames is [bug 26440](https://www.w3.org/Bugs/Public/show_bug.cgi?id=26440), blocked on [bug 28001](https://www.w3.org/Bugs/Public/show_bug.cgi?id=28001), but this is easily overlooked.

CC @domenic

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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/fullscreen/issues/16