RFR: 8324658: Allow animation play/start/stop/pause methods to be called on any thread [v9]

[Nir Lisker]

On Mon, 29 Jan 2024 13:07:21 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> I don't think this will do what you want. This will return almost immediately, before any of the animation has run (as soon as the runnable that sets the uncaught exception handler finished).

I observed that this setup works correctly for the `AnimationTimer` test. The test does wait for `GRACE_PERIOD` seconds when there is no exception and then succeeds, or catches and fails immediately when there onw is thrown. The `Animation` test was more finicky, but I think that is because I'm not simulating a processing load properly.

> The await ensures that the uncaught exception handler has been registered before starting the threads. 

While technically true, the handler register in a negligible amount of time compared to the grace period. Because exceptions are thrown continuously )it's not a one-time event), the handler will never miss a failure.

I will change it for correctness sake.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1352#discussion_r1469783805