Open Radar

 
Summary:
When doing a custom .CurrentContext animation inside a container view (from a storyboard) the presentation transition adds the presented view controller's view (fromView) to a `UITransitionView`. 

When dismissing the presented view controller the toView should be added to the `UITransitionView`, which is cleaned up after the transition finishes. During this cleanup the toView is taken from the `UITransitionView` and added back at the wrong place in the view hierarchy.

It should be added back as a subview of the container view (from which it came), instead it appears to be added as a subview of the rootViewController's transitionView.

Steps to Reproduce:
1. Have a view controller with a custom .CurrentContext transition
2. Present the view controller using the custom transition
3. Dismiss the view controller

Expected Results:
The view hierarchy to be restored to the state it was in before the presentation (or the visual equivalent of that).

Actual Results:
The view hierarchy ends up with the toView at the wrong place.