RFR: 8241840: Memoryleak: Closed focused Stages are not collected with Monocle. [v5]

[Kevin Rushforth]

On Wed, 22 Apr 2020 12:03:34 GMT, Florian Kirmaier <fkirmaier at openjdk.org> wrote:

>> Closed focused Stages are not collected with Monocle
>> 
>> This commit adds a unit-test and a fix for collecting focused closed stages.
>> 
>> ticket: https://bugs.openjdk.java.net/browse/JDK-8241840
>
> Florian Kirmaier has updated the pull request incrementally with one additional commit since the last revision:
> 
>   JDK-8241840
>   The tests are now reused for native and monocle tests.

The fix looks good now. I'll file a follow-up issue for the potential leak on the other platforms.

My thinking is that if `focusedWindow` is only used in Monocle, we should push the tracking down to the platform rather
than tracking it in the base class. Alternatively, we could have a platform-specific attribute that indicates whether
to track (and leave it null otherwise).

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PR: https://git.openjdk.java.net/jfx/pull/153