Summary: Views that can contain other Views need to have their ViewManager to extend ViewGroupManager. Otherwise, it may not remove child Views correctly when a parent View is being detached. This diff is changing FlatViewManager that create FlatViewGroups (that can have child Views) to extend from ViewGroupManager.
Reviewed By: ahmedre
Differential Revision: D2768667
Summary: @public There are some properties that we want to handle on a View level, as opposed to a FlatShadowNode level. For example, scale or alpha, that can be done very efficiently in hardware. Once we pop FlatShadowNode to a separate View, we need to apply these properties. This is where `BaseViewManager` comes in handy.
Reviewed By: sriramramani
Differential Revision: D2694290
Summary: @public This diff adds a `FlatShadowNode.forceMountToView()` method that will render its contents in it own `View`.
Reviewed By: sriramramani
Differential Revision: D2564502
Denis Koroskin