RFR: 8338688: Shenandoah: Avoid calling java_lang_Class accessors in asserts/verifier

[William Kemper]

Trivial to resolve.

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Commit messages:
 - Backport e297e8817f486e4af850c97fcff859c3e9a9e21c

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/128/files
  Webrev: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=128&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8338688
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/128.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/128/head:pull/128

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/128