bug 930059 - Overscroll.java doesn't need to use compatibility libraries r=wesj

--HG--
rename : mobile/android/base/gfx/Overscroll.java => mobile/android/base/gfx/OverscrollEdgeEffect.java
bug 930059 - Overscroll.java doesn't need to use compatibility libraries, follow up to not use invalidateAfterAnnimation on ICS r=wesj