We would trigger assertion failures in Debug mode, and fail to
parse and translate correctly in Release.

BUG=angle:711

Change-Id: Ibb7f33b288376617598578f48c7bbdbdec044279
Reviewed-on: https://chromium-review.googlesource.com/210822Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Nicolas Capens <capn@chromium.org>