Summary:
Initial implementation of Litho extensions using mount extension. After mount is called on the main thread and we traverse the hierachy. In future we can use mount extensions to construct a sparse tree rather than sending everything every time.
Scroll is handled with a native UI scroll listener for each litho view. This may break if the litho view is not a direct child of the scroll view.
Reviewed By: mihaelao
Differential Revision: D40021840
fbshipit-source-id: b09086a7a16660225885620609009dddf5b90d3b
1aacc51d12