This allows handling them without ever needing to offscreen for losing
the clip, because the clip can always be transformed.
Also, all the optimizations keep working, like occlusion culling,
clears, and so on.
The main benefit of this work is the ability for offloading to now
handle dihedral transforms of the video buffer.
The other big advantage is that we can now start our rendering with a
dihedral transform from the compositor.
