Class methods should be non enumerable

src/runtime/runtime-classes.cc

Index: src/runtime/runtime-classes.cc
diff --git a/src/runtime/runtime-classes.cc b/src/runtime/runtime-classes.cc
index e4a29058c2b2ff1063875956dd742f4307b5f5e2..8a207a8eabcea60d5b12d844e1f97199495af936 100644
--- a/src/runtime/runtime-classes.cc
+++ b/src/runtime/runtime-classes.cc
@@ -166,11 +166,12 @@ RUNTIME_FUNCTION(Runtime_DefineClassMethod) {
   uint32_t index;
   if (name->AsArrayIndex(&index)) {
     RETURN_FAILURE_ON_EXCEPTION(
-        isolate, JSObject::SetOwnElement(object, index, function, STRICT));
+        isolate,
+        JSObject::SetOwnElement(object, index, function, DONT_ENUM, STRICT));
   } else {
     RETURN_FAILURE_ON_EXCEPTION(
-        isolate,
-        JSObject::SetOwnPropertyIgnoreAttributes(object, name, function, NONE));
+        isolate, JSObject::SetOwnPropertyIgnoreAttributes(object, name,
+                                                          function, DONT_ENUM));
   }
   return isolate->heap()->undefined_value();
 }