Modify scroll to take element argument.

Originally, scroll scrolls insider the first ScrollView. However, most of our ScrollViews is CollectionView, or TableView. So, we got error that the ScrollView could not found, although there are multiple "ScrollViews".

We also need to able to scroll insider different scrollviews.
Merge pull request #2213 from bootstraponline/2194_squashed

Modify scroll to take element argument.