Ability to scroll a specific item in a tree into view

[jrafidi]

Would like to be able to scroll a specific item in a tree into view. This is useful for any feature where interactions outside of the tree need to reveal something inside of the tree. Couldn't find a way to do it using the existing component.

[jkillian]

Talked this over with @giladgray and decided to go about it this way:

• Add a Tree#getNodeRef function to core Blueprint
• Application code can then implement this functionality themselves:
  • expand all parents of a given node
  • call myTreeRef.getNodeRef("myNode").scrollIntoView()