diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_8_5/extensions/regress-668438.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_8_5/extensions/regress-668438.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+// -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+// Any copyright is dedicated to the Public Domain.
+// http://creativecommons.org/licenses/publicdomain/
+
+// Don't assert trying to parse this.
+let(x = (x(( function() { 
+                 return { e: function() { e in x } };
+             }))
+         for (x in [])))
+true;
+
+reportCompare(true, true);