This produces undefined pixel values in GL. We can also return UNSUPPORTED if required and still be conformant. This fixes an assert in the gfx-rs portability implementation. Bug: angleproject:5601 Change-Id: Ifb84ad9b5e2365360a81cddba766b0bea81f2d51 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2668311 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
