[lworld] RFR: 8376652: [lworld] Explicit and consistent names for nonstatic fields in FieldLayout

[Joel Sikström]

Hello,

We should be explicit when naming variables that refer to "fields" and state whether we mean staitc or nonstatic fields.

I've also done a bit of cleanup in `FieldLayoutBuilder::compute_inline_class_layout()`, which calls `has_nonstatic_fields`. The "has_nonstatic_fields" property is inherited from the superklass whenever a klass instance is created, so we only have to check the property once on the "first" superklass.

Testing:
* Oracle's tier1-3, jdk_valhalla and hotspot_valhalla
* I added an assert to sanity test that the while loop I removed in `FieldLayoutBuilder::compute_inline_class_layout()` never gets past the "first" superklass, which didn't hit in tier1-3.

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Commit messages:
 - 8376652: [lworld] Explicit and consistent names for nonstatic fields in FieldLayout

Changes: https://git.openjdk.org/valhalla/pull/1992/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1992&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376652
  Stats: 26 lines in 2 files changed: 2 ins; 11 del; 13 mod
  Patch: https://git.openjdk.org/valhalla/pull/1992.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1992/head:pull/1992

PR: https://git.openjdk.org/valhalla/pull/1992