I would be very surprised if Apple took the time to re-write the rendering engine but didn't also work on the UI. I suspect that when this new rendering engine

I would be very surprised if Apple took the time to re-write the rendering engine but didn't also work on the UI. I suspect that when this new rendering engine launches, it will probably wrapped in a UI that copies most of the innovations of Chrome (and hopefully improves on them) in the same way that Chrome took a lot from others.