RFR: 8319103: Popups that request focus are not shown on Linux with Wayland

[Alexander Zvegintsev]

This is the fix for the regression introduced in [JDK-8280993](https://bugs.openjdk.org/browse/JDK-8280993).

That fix was to dismiss a popup if the owner loses the window focus when running in Wayland, and didn't take into account that the popup itself can be focusable.

This fix closes the popup only if the focus moves away from the calling window and the popup itself.

There is no jtreg test provided because it requires transferring the window focus to a non-X11 window, and our current robot implementation [does not allow this](https://bugs.openjdk.org/browse/JDK-8280983).

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Commit messages:
 - 8319103: Popups that request focus are not shown on Linux with Wayland

Changes: https://git.openjdk.org/jdk/pull/16636/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16636&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319103
  Stats: 34 lines in 1 file changed: 27 ins; 5 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/16636.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16636/head:pull/16636

PR: https://git.openjdk.org/jdk/pull/16636