localToAbsolute() and absoluteToLocal() need to correctly map points through 3d transforms, taking perspective and transform-style into account.
Created attachment 27943 [details]
I have extensive test cases, but I can't land them until bug 23943 is landed, and/or we fix hit testing for 3d. So they will come later.
Comment on attachment 27943 [details]
Put TransformState in its own file and don't worry about it being a nested RenderObject struct. Everything else looks fine to me.