Properly restore RTL state in HorizontalScrollView

Fix an incorrect unparceling of the previous saved state in
HorizontalScrollView. Remove an unneeded field in the saved state by
storing scroll offset from start instead of scrollX + isRtl.

Bug 20666194

Change-Id: I1ec45b3e3bd0846b5f659356df7ff94f42e61055
1 file changed