Fix buildbot_result output for a test that fails unexpectedly twice.

If a test failed unexpectedly, then failed unexpectedly in a different way
on the retry, run-webkit-tests would print that it was a flake rather than
a regression.

TBR=ojan@chromium.org
BUG=415316

Review URL: https://codereview.chromium.org/571373003

git-svn-id: svn://svn.chromium.org/blink/trunk@183290 bbb929c8-8fbe-4397-9dbb-9b2b20218538