RFR: 8313956: focusWithin on parents of a newly-added focused node is not updated [v4]

[Marius Hanl]

On Fri, 18 Aug 2023 20:45:00 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> This PR fixes an issue with the way `focusWithin` bits are adjusted in the scene graph. Previously, the `focusWithin` counts of all parents of a removed node would be decreased if the removed node has a non-zero `focusWithin` count. This PR adds logic for the opposite scenario: the `focusWithin` count is increased on all parents of a newly-added node that is already focused (or contains other focused nodes).
>
> Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Changes per review

Marked as reviewed by mhanl (Committer).

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PR Review: https://git.openjdk.org/jfx/pull/1210#pullrequestreview-1585259950