Buck no longer accepts duplicate deps. One test listed a library
that is always included for tests and can be safely dropped.
Buck does not accept duplicate resources, which happens with
gwt_module() loading in srcs, resources and gwt_xml. Convert
to a set and back to a list to remove duplicates transparently.
Change-Id: I0e450ef376040e8fa315ca17ab62a5cebbaf1d67