RFR: 8261262: Kitchensink24HStress.java crashed with EXCEPTION_ACCESS_VIOLATION

Mon Mar 15 11:53:20 UTC 2021

When returning from the last Java frame back to vm and hitting a safepoint poll on that last return we sometimes have a last java frame but no vframe.
This seem to be a bug in itself, handled in: 8263576

Other places which uses vframe NULL checks it before, so let's do that in GetCurrentLocationClosure also.

Testing: nsk jdi/jvmti, jdk jdi, jck vm and t1-3.

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Commit messages:
 - Check vframe non-null

Changes: https://git.openjdk.java.net/jdk/pull/3010/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3010&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261262
  Stats: 9 lines in 1 file changed: 0 ins; 3 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3010.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3010/head:pull/3010

PR: https://git.openjdk.java.net/jdk/pull/3010