Switch to t.A syntax for synthesized types.  Allow the user to refer to such as type.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/constructors_with_record2@14516 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Remove debug.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/constructors_with_record2@14517 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02