This PR adds the `-fx-supports-conditional-feature` media query, which allows applications to adapt their stylesheets to different platforms with varying conditional feature support. Currently, the built-in themes use hard-coded logic to include or exclude conditional-feature stylesheets. The new media query allows us to potentially remove the hard-coded logic in the future, and gives third-party themes an API to query conditional feature support.
--------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - ConditionalFeature media queries Changes: https://git.openjdk.org/jfx/pull/2161/files Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=2161&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8374804 Stats: 151 lines in 4 files changed: 143 ins; 0 del; 8 mod Patch: https://git.openjdk.org/jfx/pull/2161.diff Fetch: git fetch https://git.openjdk.org/jfx.git pull/2161/head:pull/2161 PR: https://git.openjdk.org/jfx/pull/2161
