--- a/js/src/frontend/EitherParser.h
+++ b/js/src/frontend/EitherParser.h
@@ -45,20 +45,20 @@ struct InvokeMemberFunction
     explicit InvokeMemberFunction(ActualArgs&&... actualArgs)
       : args { mozilla::Forward<ActualArgs>(actualArgs)... }
     {}
 
     template<class Parser>
     auto
     match(Parser* parser)
       -> decltype(this->matchInternal(GetThis<Parser>::get(parser),
-                                      typename mozilla::IndexSequenceFor<Args...>::Type()))
+                                      std::index_sequence_for<Args...>))
     {
         return this->matchInternal(GetThis<Parser>::get(parser),
-                                   typename mozilla::IndexSequenceFor<Args...>::Type());
+                                   std::index_sequence_for<Args...>);
     }
 };
 
 // |this|-computing templates.
 
 template<class Parser>
 struct GetParser
 {