In order to make the errors be consistent throughout ANGLE.

BUG=angleproject:1686

Change-Id: I0a2d86091d640aedeac94beae345c1fb6971b00d
Reviewed-on: https://chromium-review.googlesource.com/424835
Commit-Queue: Yunchao He <yunchao.he@intel.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>