[lworld] RFR: 8376814: [lworld] ValueCompositionTest doesn't support NULLABLE_NON_ATOMIC_FLAT layout

[Frederic Parain]

Simple test update to cover NULLABLE_NON_ATOMIC_FLAT layout.

Tested with Mach5 tier1.

Fred

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Commit messages:
 - Update test to cover NULLABLE_NON_ATOMIC_FLAT

Changes: https://git.openjdk.org/valhalla/pull/2040/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2040&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376814
  Stats: 45 lines in 1 file changed: 37 ins; 1 del; 7 mod
  Patch: https://git.openjdk.org/valhalla/pull/2040.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2040/head:pull/2040

PR: https://git.openjdk.org/valhalla/pull/2040