RFR: 8251555: Remove unused focusedWindow field in glass Window to avoid leak

[Ambarish Rapte]

On Sat, 22 Aug 2020 19:39:33 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> This is a follow-up to [JDK-8241840](https://bugs.openjdk.java.net/browse/JDK-8241840) that removes an unused static
> `focusedWindow` field and its associated getter and setter from the platform-independent glass Window class. This is
> entirely unused by any of the glass platforms. The Monocle platform keeps track of the `focusedWindow` attribute
> itself.  The existing `test.javafx.stage.FocusedWindowNativeTest` automated test, which was added as part of
> [JDK-8241840](https://bugs.openjdk.java.net/browse/JDK-8241840), was failing fairly consistently on one of our test
> machines before this fix, and now passes.

Looks good to me.

-------------

Marked as reviewed by arapte (Reviewer).

PR: https://git.openjdk.java.net/jfx/pull/286