RFR: 8258032: Reconsider LEAF entry restrictions [v2]

[Coleen Phillimore]

> Please review the smaller version of this enhancement.  JRT_LEAF can allow Handles.  Fixed places where a ResetNoHandleMark was added to workaround the restriction and remove some obsolete comments in deoptimization (the function is a JRT_BLOCK_ENTRY that has a HandleMarkCleaner which cleans up the HandleMark to the one before call_stub() in JavaCalls. A HandleMarkCleaner also allows HandleMark and Handles.
> 
> Tested with tier1-3, 4-6 with the larger change and 7-8 in progress.

Coleen Phillimore 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 six additional commits since the last revision:

 - Revert zVerify and stackWaterMark changes.  They need a RNHM.
 - Remove ResetNoHandleMark after ThreadInVMfromNative.
 - Merge branch 'master' into leaf2
 - Merge branch 'master' into leaf2
 - Remove slow_identity_hash ResetNoHandleMark
 - 8258032: Reconsider LEAF entry restrictions

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1990/files
  - new: https://git.openjdk.java.net/jdk/pull/1990/files/85c89b61..4e66f0ac

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1990&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1990&range=00-01

  Stats: 21319 lines in 663 files changed: 10586 ins; 7128 del; 3605 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1990.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1990/head:pull/1990

PR: https://git.openjdk.java.net/jdk/pull/1990