Code sinking cleanups

* Reword/refactor sinking throwing instructions
* Removed redundant GetSuccessors().empty() check
* Created a check in GraphCheker regarding no successors
* Update gtest to comply with the new check
* Typo fixes

Test: art/test/testrunner/testrunner.py --host --64 --optimizing -b
Change-Id: Ibf27266f29570a4b1b63bb9bd80e5906207527c0
3 files changed