Double input focus and focus movement in list not working.

1. The clearFocus routine in ViewGroup was clearing the pointer
   to the descendant which has focus after calling clear focus
   on that child. However, currently clearing the focus of a view
   causes the view that loses focus to try to give the focus to
   the first focusable which potentially sets the pointer to the
   child that has input focus in the ViewGroup but the ViewGruop
   essentially clears that pointer. This resulted in having two
   focused views at the same time in some cases.

2. AbsListView was not calling the super implementation of add
   focusables if the focus type was not accessibility.

bug:6559819

Change-Id: I478dfed000b5de3f9b15e12eb82aa3d34c2301e4