[lworld] Integrated: 8271389: [lworld] Improve typing of primitiveObject.getClass()

[Srikanth Adayapalam]

Static type of getClass() should align with behavior of method which always returns the primary mirror.

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Commit messages:
 - 8271389: [lworld] Improve typing of primitiveObject.getClass()

Changes: https://git.openjdk.java.net/valhalla/pull/505/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=505&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271389
  Stats: 70 lines in 6 files changed: 43 ins; 13 del; 14 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/505.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/505/head:pull/505

PR: https://git.openjdk.java.net/valhalla/pull/505