AppCompat ListPopupWindow fixes

- Fixes Spinner jumping back on Gingerbread due to
  a call to setSelection(). The framework uses setSelectionInt()
  which we don't have access to. There's no side-effects to removing
  this call from my testing.
- Use AbsListView.scrollListBy() on API 19+, makes drag-to-open
  scrolling much smoother on those platforms.

BUG: 26393526
BUG: 25085519

Change-Id: Iaafc2be81c8a9ff161e5506700668020030ee52d
6 files changed