Music: Displaying blank space while moving songs

The view being dragged will be set as invisible if it is
the last item of listview

Do not set invisible for last item

Change-Id: Icf0d6922aa9b6127e6caa555c5ac7b919c57df08
CRs-Fixed: 2003749
diff --git a/src/com/android/music/TouchInterceptor.java b/src/com/android/music/TouchInterceptor.java
index b5c3696..0b15d2d 100755
--- a/src/com/android/music/TouchInterceptor.java
+++ b/src/com/android/music/TouchInterceptor.java
@@ -313,9 +313,14 @@
                 }
             } else if (vv.equals(first)) {
                 // processing the item that is being dragged
-                if (mDragPos == mSrcDragPos || getPositionForView(vv) == getCount() - 1) {
+                if (mDragPos == mSrcDragPos) {
                     // hovering over the original location
                     visibility = View.INVISIBLE;
+                } else if (getPositionForView(vv) == getCount() - 1) {
+                    // Children views will be set Visible in unExpandViews(), and it use
+                    // getChildAt(i) to get these children, but if we set INVISIBLE for last
+                    // item here, getChildAt() in unExpandViews() will return null(Why? I don't
+                    // know neither), and unExpandViews can not restore views' visibility
                 } else {
                     // not hovering over it
                     // Ideally the item would be completely gone, but neither