Fix potential NPE if there is no child in HorizontalScrollView
Fix potential NPE if there is no child in HorizontalScrollView

- related to the previous change for saving the scroll position
- also related to bug #9463581 NPE observed while launching News&Weather app from all apps tray

Change-Id: I9f2f8a246e793eefa1cf510e15a56a1058fb9c18

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base