[jdk15u-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 jdk15u for parity with jdk11u.
The original patch applied cleanly.
All regular tests passed.

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Commit messages:
 - Backport 685c03dc4899e4f43e830d516b751969ed20ec21

Changes: https://git.openjdk.java.net/jdk15u-dev/pull/101/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk15u-dev&pr=101&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/jdk15u-dev/pull/101.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk15u-dev pull/101/head:pull/101

PR: https://git.openjdk.java.net/jdk15u-dev/pull/101