[code-reflection] RFR: Fix SSABraun bug and add SSA tests

[Ruby Chen]

Fix a bug in SSABraun where, in `tryRemoveTrivialPhi()`, a trivial phi is not removed from its own user list before `phi.replaceBy(same, this)` is called to replace all users of the trivial phi.  

Add five tests to TestSSA: `deadCode(), ifelseLoopNested(), violaJones(), binarySearch(),` and `quicksort()`. `violaJones()` is inspired by the method `findFeaturesKernel` in HAT kernel ViolaJones.

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

Commit messages:
 - Fix SSABraun bug and add SSA tests

Changes: https://git.openjdk.org/babylon/pull/542/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=542&range=00
  Stats: 156 lines in 2 files changed: 153 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/babylon/pull/542.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/542/head:pull/542

PR: https://git.openjdk.org/babylon/pull/542