A slight bug in the problem case detection applied the workaround
overly-broadly. Also included a much more thorough test.

BUG=angleproject:851

Change-Id: I5c09d67eee3622c144401769af85958f23b60c57
Reviewed-on: https://chromium-review.googlesource.com/371380Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>