RFR: 8302260: VarHandle.describeConstable() fails to return a nominal descriptor for static public fields

[Mandy Chung]

I overlooked in the fix for JDK-8297757 that it should have passed the declaring class of the static fields rather than the reference class passed to `Lookup::findStaticVarHandle`.

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Commit messages:
 - 8302260: VarHandle.describeConstable() fails to return a nominal descriptor for static public fields

Changes: https://git.openjdk.org/jdk/pull/12543/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12543&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302260
  Stats: 231 lines in 7 files changed: 190 ins; 0 del; 41 mod
  Patch: https://git.openjdk.org/jdk/pull/12543.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12543/head:pull/12543

PR: https://git.openjdk.org/jdk/pull/12543