RFR: 8342524: Use latch in AbstractButton/bug6298940.java instead of delay [v2]

[Alexander Zvegintsev]

On Wed, 29 Jan 2025 15:46:31 GMT, Alexey Ivanov <aivanov at openjdk.org> wrote:

>> Use a `CountDownLatch` in `javax/swing/AbstractButton/bug6298940.java` instead of delay.  
>> Use `Util.hitMnemonics` instead of custom code to handle macOS.
>> 
>> I ran the updated test a few times with `JTREG=REPEAT_COUNT=20`, the test always passed in the CI.
>
> Alexey Ivanov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Check for null before dispose()

Marked as reviewed by azvegint (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/23301#pullrequestreview-2581793437