[lworld] RFR: 8342033: [lworld] Rename ClassDescImpl back to ReferenceClassDescImpl

[David Simms]

ClassDescImpl -> ReferenceClassDescImpl

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Commit messages:
 - 8342033: [lworld] Rename ClassDescImpl back to ReferenceClassDescImpl

Changes: https://git.openjdk.org/valhalla/pull/1277/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1277&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342033
  Stats: 377 lines in 13 files changed: 135 ins; 135 del; 107 mod
  Patch: https://git.openjdk.org/valhalla/pull/1277.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1277/head:pull/1277

PR: https://git.openjdk.org/valhalla/pull/1277