Walk through a M3Context.T and add a property to each
   node that represents a type specification that is not
   a named type. The property added is the name of the type
   specified (precicly one name of the type).
   This typename is later used instead of the type specification
   (see AstToType.AddToTable).
INTERFACETypeNames ; IMPORT M3Context; PROCEDURE Preprocess(c: M3Context.T); END TypeNames.