[code-reflection] RFR: Exception regions fix [v4]

[Adam Sotona]

> BytecodeGenerator::computeExceptionRegionMembership now collects all necessary info into BitSets and directly declares the regions with CodeBuilder.
> All tests are now passing.
> 
> Please review.
> 
> Thanks,
> Adam

Adam Sotona has updated the pull request incrementally with two additional commits since the last revision:

 - initial version of BranchCompactor skipping branches to immediate targets
 - removed obsolete imports

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

Changes:
  - all: https://git.openjdk.org/babylon/pull/12/files
  - new: https://git.openjdk.org/babylon/pull/12/files/333751d7..779a658c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=12&range=03
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=12&range=02-03

  Stats: 123 lines in 7 files changed: 100 ins; 15 del; 8 mod
  Patch: https://git.openjdk.org/babylon/pull/12.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/12/head:pull/12

PR: https://git.openjdk.org/babylon/pull/12