Skip `StageFocusTest` on Linux until [JDK-8367893](https://bugs.openjdk.org/browse/JDK-8367893) is fixed.
Also tested on macOS and Windows to verify that the test is still run. ------------- Commit messages: - 8367898: Skip StageFocusTest on Linux Changes: https://git.openjdk.org/jfx/pull/1909/files Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1909&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8367898 Stats: 6 lines in 1 file changed: 6 ins; 0 del; 0 mod Patch: https://git.openjdk.org/jfx/pull/1909.diff Fetch: git fetch https://git.openjdk.org/jfx.git pull/1909/head:pull/1909 PR: https://git.openjdk.org/jfx/pull/1909
