RFR: 8255216: ciEnv::_break_at_compile isn't in use [v2]

[Dan]

> _break_at_compile is no longer in use and can be safely removed.
> No new code, and Tier1 tests succeed after code is removed.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8255216

Dan has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains one commit:

  8255216: ciEnv::_break_at_compile isn't in use
  
  _break_at_compile is no longer in use and can be safely removed.
  No new code, and Tier1 tests succeed after code is removed.
  
  Bug: https://bugs.openjdk.java.net/browse/JDK-8255216

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

Changes: https://git.openjdk.java.net/jdk/pull/1806/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1806&range=01
  Stats: 11 lines in 3 files changed: 0 ins; 11 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1806.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1806/head:pull/1806

PR: https://git.openjdk.java.net/jdk/pull/1806