RFR: 8324658: Allow animation play/start/stop/pause methods to be called on any thread [v14]

[Nir Lisker]

On Mon, 29 Jan 2024 16:42:15 GMT, Nir Lisker <nlisker at openjdk.org> wrote:

>> Added a utility method to run code on the FX thread if it's not already, and changed the animation methods to use it.
>
> Nir Lisker has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update tests

The tests are a best-effort to reproduce the issue and may pass even before the fix.

I found that the `AnimationTimer` test cases can fail in 2 ways: one is the reported NPE on the FX thread, but another is an AIIOB on the background thread that originates in (or close to) the master timer. For this reason, I added exception handlers on the FX and on each background thread.

The `Animation` test is more unstable, maybe because it doesn't simulate a load on every tick (like in `AnimationTimer::handle()`). Maybe using a `Timer` implementation instead of a `Transition` will allow to reproduce the issue better.

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PR Comment: https://git.openjdk.org/jfx/pull/1352#issuecomment-1915141156