Experience in building FX apps has shown that boundsInScene is rarely used (I'm not even aware of anybody using it currently, except maybe in one demo). It can be computed by developers with a simple bound function.

However, boundsInScene contributes greatly to the cost of updating the scene graph. Without bounds in scene we could:
    - Remove notification of transformed bounds changes
    - Refactor painting to compute transformed bounds as it goes rather than needing transformed bounds ahead of time
        - This would allow us to no longer cache or use transformed bounds
        - This would allow us to remove walking down the tree when transforms change (there are a couple niggles but it should be true)

Walking down the tree has been shown to cut in half our FPS in some situations (such as BrickBreaker with lots of balls).