RFR: 8300237: Minor improvements in MethodHandles

[Sergey Tsypanov]

- `MethodType.ptypes()` can be used instead of `MethodType.parameterList()` when we don't need a copy
- comparison of two lists can be done without `Stream.reduce()`

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Commit messages:
 - Fix test
 - Improve MH

Changes: https://git.openjdk.org/jdk/pull/12025/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12025&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8300237
  Stats: 14 lines in 1 file changed: 2 ins; 6 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/12025.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12025/head:pull/12025

PR: https://git.openjdk.org/jdk/pull/12025