Update fast scroll shadow to match other shadows

    private static final float FAST_SCROLL_OVERLAY_Y_OFFSET_FACTOR = 1.5f;

    private static final int SHADOW_INSET = 5;

    private static final int SHADOW_SHIFT_Y = 4;

    private static final float SHADOW_ALPHA_MULTIPLIER = 0.5f;

    private static final int SHADOW_INSET = 3;

    private static final int SHADOW_SHIFT_Y = 2;

    private static final float SHADOW_ALPHA_MULTIPLIER = 0.67f;

    private Resources mRes;

    private BaseRecyclerView mRv;