diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_8_5/regress/regress-597945-2.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_8_5/regress/regress-597945-2.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ */
+
+var a = {d: true, w: true};
+Object.defineProperty(a, "d", {set: undefined});
+delete a.d;
+delete a.w;
+a.d = true;
+
+reportCompare(0, 0, "ok");