Align the sample position in blitResolveStencil compute shader The input coordinates of blitResolveStencil compute shader start from 0,we need to align the sample position to start from 0 if x/y is flipped. Test: dEQP-GLES3.functional.fbo.invalidate.*.unbind_blit_msaa_* Bug: b/159995959 Change-Id: If0c9f5b7cacddbe1a2d7062469a757a63bcc1378 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2392162 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Ian Elliott <ianelliott@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org>