Currently the EventSender can simulate starting dragss, but not simulate a drop. This requires first landing rudimentary leapForward support, which includes the basic logic for walking the event queue.
Created attachment 58918 [details] Patch for this issue
Comment on attachment 58918 [details] Patch for this issue Simpler than I was expecting, tbh =)
Committed r64082: <http://trac.webkit.org/changeset/64082>