When an element has backface-visibility:hidden, it needs to get a RenderLayer (and maybe be stacking context)?
Has this bug been fixed already? It seems that modern WebKit-based browsers do create RenderLayers for elements with backface-visibility:hidden.
Is https://bugs.webkit.org/show_bug.cgi?id=81134 resolved duplicate of this bug?
Yep. *** This bug has been marked as a duplicate of bug 81134 ***