RFR: 8324658: Allow animation play/start/stop/pause methods to be called on any thread [v17]

[Kevin Rushforth]

On Tue, 30 Jan 2024 01:24:52 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 updated test looks good. I verified that it will correctly fail if [JDK-8159048](https://bugs.openjdk.org/browse/JDK-8159048) is reintroduced, and will also fail without the fix for _this_ issue (that is, with the current jfx master).

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Marked as reviewed by kcr (Lead).

PR Review: https://git.openjdk.org/jfx/pull/1352#pullrequestreview-1850112597