It looks like the following tests regressed in r67098 (on Windows): animations/fill-mode-missing-from-to-keyframes.html animations/fill-mode-multiple-keyframes.html animations/fill-mode-transform.html animations/fill-mode.html
We simply had no tests before that tested animation-direction. Bug 46017 will fix this. *** This bug has been marked as a duplicate of bug 46017 ***