remove comment

Author: zth

jscomp/ml/predef.ml

@@ -234,7 +234,7 @@ let common_initial_env add_type add_extension empty_env =
           ld_id = ident_dict_magic_field_name;
           ld_attributes = [(Location.mknoloc "res.optional", Parsetree.PStr []); Dict_type_helpers.dict_magic_field_attr];
           ld_loc = Location.none;
-          ld_mutable = Immutable; (* TODO(dict-pattern-matching) Should probably be mutable? *) 
+          ld_mutable = Immutable;
           ld_type = newgenty (Tconstr (path_option, [tvar], ref Mnil));
         }], 
         Record_optional_labels [Ident.name ident_dict_magic_field_name]);