BUG=angleproject:2376
TEST=dEQP-GLES31.functional.debug.negative_coverage.get_error.buffer.invalidate_sub_framebuffer

Change-Id: Ie1ca30f29d7583c86130f46d4e6b5c7211eee63a
Reviewed-on: https://chromium-review.googlesource.com/938367Reviewed-by: Jiawei Shao <jiawei.shao@intel.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>