[jdk17u-dev] RFR: 8295026: Remove unused fields in StyleSheet

[Goetz Lindenmaier]

I backport this for parity with 17.0.12-oracle.

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

Commit messages:
 - Backport be3b3354523917c024fb9d7d99de7c7eec3d175a

Changes: https://git.openjdk.org/jdk17u-dev/pull/2363/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2363&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295026
  Stats: 5 lines in 1 file changed: 0 ins; 5 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2363.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2363/head:pull/2363

PR: https://git.openjdk.org/jdk17u-dev/pull/2363