Fixing regression in fast scroller animation.

- Fast scroller was not fading out since we were missing the getter
  for the fast scroller alpha (so the initial alpha to animate from
  was wrong).

Change-Id: I2fd13eee3deb084ba37cf4a849e2378f23758391
diff --git a/src/com/android/launcher3/BaseRecyclerView.java b/src/com/android/launcher3/BaseRecyclerView.java
index a207d9a..3a741f2 100644
--- a/src/com/android/launcher3/BaseRecyclerView.java
+++ b/src/com/android/launcher3/BaseRecyclerView.java
@@ -290,6 +290,13 @@
     }
 
     /**
+     * Returns the fast scroller alpha.
+     */
+    public float getFastScrollerAlpha() {
+        return mFastScrollAlpha;
+    }
+
+    /**
      * Maps the touch (from 0..1) to the adapter position that should be visible.
      * <p>Override in each subclass of this base class.
      */