[jdk17] RFR: 8269285: Crash/miscompile in CallGenerator::for_method_handle_inline after JDK-8191998

[Aleksey Shipilev]

See the bug report for more details.

I believe the [JDK-8191998](https://bugs.openjdk.java.net/browse/JDK-8191998) change introduced a slight regression, where the speculative type join may empty the type. It would then crash on assert in `fastdebug` builds, or miscompile the null-check to `true` in `release` bits. New test captures both failure modes.

This is not a recent regression, but a regression nevertheless, so I would like to have that fix in JDK 17. Please review carefully, or speak up if you want to move it to JDK 18+ and then backport later.

Additional testing:
 - [x] New test fails without the patch, passes with it
 - [x] Linux x86_64 `fastdebug` `tier1`

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Commit messages:
 - 8269285: Crash/miscompile in CallGenerator::for_method_handle_inline after JDK-8191998

Changes: https://git.openjdk.java.net/jdk17/pull/169/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17&pr=169&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269285
  Stats: 69 lines in 2 files changed: 65 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/169.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/169/head:pull/169

PR: https://git.openjdk.java.net/jdk17/pull/169