[jdk11u-dev] RFR: 8290198: Shenandoah: a few Shenandoah tests failure after JDK-8214799 11u backport

[Zhengyu Gu]

Please review this patch that fixes Shenandoah test failures after JDK-8214799 11u backport.

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

Commit messages:
 - 8290198: Shenandoah: a few Shenandoah tests failure after JDK-8214799 11u backport

Changes: https://git.openjdk.org/jdk11u-dev/pull/1220/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1220&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8290198
  Stats: 37 lines in 6 files changed: 9 ins; 17 del; 11 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1220.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1220/head:pull/1220

PR: https://git.openjdk.org/jdk11u-dev/pull/1220