Add PlatformUtil.isHeadless() method. Use that in tests to conditionally skip tests.
Fix JDK-8364203 ------------- Commit messages: - Add PlatformUtil.isHeadless() method. Changes: https://git.openjdk.org/jfx/pull/1859/files Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1859&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8364203 Stats: 11 lines in 2 files changed: 8 ins; 0 del; 3 mod Patch: https://git.openjdk.org/jfx/pull/1859.diff Fetch: git fetch https://git.openjdk.org/jfx.git pull/1859/head:pull/1859 PR: https://git.openjdk.org/jfx/pull/1859
