[jdk17u-dev] RFR: 8306428: RunThese30M.java crashed with assert(early->flag() == current->flag() || early->flag() == mtNone)

[Martin Doerr]

Backport of [JDK-8306428](https://bugs.openjdk.org/browse/JDK-8306428). Includes [JDK-8271406](https://bugs.openjdk.java.net/browse/JDK-8271406) to make the backport clean (see 1st commit, touched lines are removed by 2nd commit).

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Commit messages:
 - Backport ca54f4e007ab0f13bec9aaf995d34c0ab3ba6452
 - Backport f2bc4476593938094263f0d85fc9bdd369e95237

Changes: https://git.openjdk.org/jdk17u-dev/pull/1491/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1491&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306428
  Stats: 8 lines in 1 file changed: 7 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1491.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1491/head:pull/1491

PR: https://git.openjdk.org/jdk17u-dev/pull/1491