This is the (evil) twin commit to:
facebook#12502

Fixes that contentOffset is not available on
Vertical scroll-views.

Verification:
* Create an Android component with a ScrollView. Add enough
  items to fill beyond the visible screen. Set the content
  offset to some value that makes the content scroll. Verify
  that it snaps to the y-axis as expected.
* Remove items so screen is no longer filled, keep content
  offset parameter. Scroll view still works but does not scroll.
* Set only one parameter to content-offset (x || y) -
  parameters are now ignored since they must be a pair.
* Remove contentOffset, scrollView still works as before.

…t_offset