title: UICollectionView scroll to item not working with horizontal direction
body: <p>I have a <code>UICollectionView</code> within a <code>UIViewController</code> with paging enabled. For some strange reason <code> collectionView.scrollToItem</code> works when the direction of the <code>collectionview</code> is <code>vertical</code> but doesn't when direction is <code>horizontal</code>. Is this there something I'm doing wrong or is this supposed to happen?</p>
  <pre><code>  //Test scrollToItem
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
      let i = IndexPath(item: 3, section: 0)
      collectionView.reloadData()
      collectionView.scrollToItem(at: i, at: .top, animated: true)
      print(&quot;Selected&quot;)
    }
  </code></pre>