Clear display lists when a View becomes GONE/INVISIBLE

We force an invalidate whenever a View becomes VISIBLE so there is
no need to keep the display list object while the view is either
GONE or INVISIBLE. In particular this clears the lists of references
kept by GLES20DisplayList, which helps the GC free large objects
such as Bitmaps.

Change-Id: Ifde0cb40baa1f35e5e6439d3bf8eab3c4c1270f0