RFR: 8378615: FFM Bound up call stub keeps JNI Global Ref to bound parameter

[Phil Race]

This fixes a problem whereby because a bound up call stub method handle holds on to the bound argument using a JNI Global Ref, GC of that object is prevented until the method handle is freed.
In the font layout code this causes us to be unable to collect fonts which are used as the bound argument.
So this fix changes from using the bound arg to using the existing scoped value font.

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Commit messages:
 - 8378615

Changes: https://git.openjdk.org/jdk/pull/29924/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29924&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8378615
  Stats: 39 lines in 1 file changed: 10 ins; 23 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/29924.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29924/head:pull/29924

PR: https://git.openjdk.org/jdk/pull/29924