Prevents massive infra failures when the tests are all broken.

This also gives the GoogleTest harness the ability to handle different
test result types.

Bug: angleproject:2552
Change-Id: Id9832e8557e2ee4e6a248a27729f67a81bf2d830
Reviewed-on: https://chromium-review.googlesource.com/1064014Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>