Two of the border-image reftests, layout/reftests/border-image/solid-image-1.html and solid-image-2.html show up slightly off on Mac, because a 1-pixel wide strip at the left edge of the top-center segment ends up very slightly too light. In solid-image-2.html this only happens at some widths. This may be related to bug 371316 (which I'm not sure was ever really fixed).

The third patch in bug 455364 changes us over to client-side image scaling for all components of a border-image on all platforms; this appears to resolve the bug (solid-image-1, -2, -2a all went to UNEXPECTED-PASS on Mac when it was landed) and logically should resolve it (as described, sounds like an issue with hardware scaling). I'm provisionally taking the fails-if()s out of reftest.list as part of my next revision of that patch.

This was fixed (some time ago) by bug 455364 for both trunk and 1.9.1.