ListView Animations (1/2)

PatchSet:
    - optimize more:
    - call provider values only when needed and do not fire them permanently.
      so just do it if scroll state changed.
    - as well go out of the setAnimation method as soon as possible. We
      handle here methods which get called 10000 times during scrolling
      so we need to be as fast as possible.

PS:
- initialize the animation modes default to off just to be sure

PS:
- move state change out of OnScrollListener
- reduce the provider value call to only one call

Change-Id: I5e49d858318420e76101fa6334ff766bd9496c83

Conflicts:
	core/java/android/widget/AbsListView.java