[jdk17u-dev] RFR: 8288139: JavaThread touches oop after GC barrier is detached

[Aleksey Shipilev]

Unclean backport to avoid a JVM crash. The source for uncleanliness is the absent `JavaThread::cast`, which I replaced back to `->as_Java_thread()`.

Additional testing:
 - [ ] Linux x86_64 fastdebug tier1 (as part of whole batch of PRs)
 - [ ] Linux x86_64 fastdebug tier2 (as part of whole batch of PRs)
 - [ ] Linux x86_64 fastdebug tier3 (as part of whole batch of PRs)

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Depends on: https://git.openjdk.org/jdk17u-dev/pull/1514

Commit messages:
 - Backport a1449886004b2f0a70f1413bb19ce3ba5c914fdf

Changes: https://git.openjdk.org/jdk17u-dev/pull/1515/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1515&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288139
  Stats: 22 lines in 4 files changed: 9 ins; 6 del; 7 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1515.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1515/head:pull/1515

PR: https://git.openjdk.org/jdk17u-dev/pull/1515