[jdk13u-dev] RFR: 8259271: gc/parallel/TestDynShrinkHeap.java still fails "assert(covered_region.contains(new_memregion)) failed: new region is not in covered_region"

[Olga Mikhaltsova]

I'd like to backport JDK-8259271 to jdk13u for parity with jdk11u.
The original patch applied manually. The patch is absolutely identical to the jdk11u patch, it also uses OrderAccess instead of Atomic because the method was moved from OrderAccess to Atomic only in JDK 14 with JDK-8234562. It's the only difference with the original patch.
All regular tests passed.

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Commit messages:
 - Backport 685c03dc4899e4f43e830d516b751969ed20ec21

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/263/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=263&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8259271
  Stats: 5 lines in 1 file changed: 4 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/263.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/263/head:pull/263

PR: https://git.openjdk.java.net/jdk13u-dev/pull/263