syntax: Clean out obsolete syntax parsing

All of these features have been obsolete since February 2014, where most have
been obsolete since 2013. There shouldn't be any more need to keep around the
parser hacks after this length of time.

src/libsyntax/fold.rs

@@ -648,6 +648,7 @@ pub fn noop_fold_type_method<T: Folder>(m: &TypeMethod, fld: &mut T) -> TypeMeth
         generics: fold_generics(&m.generics, fld),
         explicit_self: fld.fold_explicit_self(&m.explicit_self),
         span: fld.new_span(m.span),
+        vis: m.vis,
     }
 }