RFR: 8261262: Kitchensink24HStress.java crashed with EXCEPTION_ACCESS_VIOLATION [v2]

[Robbin Ehn]

> 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.

Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Typo
 - Merge branch 'master' into 8261262
 - Check vframe non-null

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3010/files
  - new: https://git.openjdk.java.net/jdk/pull/3010/files/50348e80..068364b6

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3010&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3010&range=00-01

  Stats: 937 lines in 72 files changed: 385 ins; 370 del; 182 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