RFR: 8336786: VerifyError with lambda capture and enclosing instance references

[Liam Miller-Cushon]

Hi, please consider this fix for [JDK-8336786](https://bugs.openjdk.org/browse/JDK-8336786). After [JDK-8334037](https://bugs.openjdk.org/browse/JDK-8334037) the handling of capturing `this` in lambdas does not handle synthetic `this` variables declared in supertypes in different packages. This change adjusts the lowering of `this` references to be owned by the enclosing class, instead of the superclass, so they are handle correctly be the capture logic in `capturedDecl` in `LambdaToMethod`.

-------------

Commit messages:
 - 8336786: VerifyError with lambda capture and enclosing instance references

Changes: https://git.openjdk.org/jdk/pull/20259/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20259&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336786
  Stats: 55 lines in 3 files changed: 52 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/20259.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20259/head:pull/20259

PR: https://git.openjdk.org/jdk/pull/20259