diff --git a/js/src/vm/JSFunction.cpp b/js/src/vm/JSFunction.cpp
--- a/js/src/vm/JSFunction.cpp
+++ b/js/src/vm/JSFunction.cpp
@@ -1184,24 +1184,26 @@ static const JSClassOps JSFunctionClassO
     fun_trace,       // trace
 };
 
 static const ClassSpec JSFunctionClassSpec = {
     CreateFunctionConstructor, CreateFunctionPrototype, nullptr, nullptr,
     function_methods,          function_properties,
 };
 
+MOZ_TT_ALLOW_REORDER
 const JSClass js::FunctionClass = {
     "Function",
     JSCLASS_HAS_CACHED_PROTO(JSProto_Function) |
         JSCLASS_HAS_RESERVED_SLOTS(JSFunction::SlotCount),
     &JSFunctionClassOps,
     &JSFunctionClassSpec,
 };
 
+MOZ_TT_ALLOW_REORDER
 const JSClass js::ExtendedFunctionClass = {
     "Function",
     JSCLASS_HAS_CACHED_PROTO(JSProto_Function) |
         JSCLASS_HAS_RESERVED_SLOTS(FunctionExtended::SlotCount),
     &JSFunctionClassOps,
     &JSFunctionClassSpec,
 };
 
