Summary:
Relies heavily on types (not) defined in other modules,
so right now it's mostly sprinkling more `any`s in.
My type declaration is based on `dts-gen` output and some
manual fixes. This is the same level as the old flow-typed
definition we had.
Reviewed By: jknoxville
Differential Revision: D17282739
fbshipit-source-id: 0e5015d3b61044615a03c50fefade908041310a8
