diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_8/genexps/regress-665286.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_8/genexps/regress-665286.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 665286;
+var summary = 'yield in arguments list';
+var actual = '';
+var expect = '';
+
+function reported() {
+    function f() {
+        x
+    }
+    f(yield [])
+}
+
+function simplified1() {
+    print(yield)
+}
+
+function simplified2() {
+    print(1, yield)
+}
+
+reportCompare(reported.isGenerator(), true, "reported case: is generator");
+reportCompare(typeof reported(), "object", "reported case: calling doesn't crash");
+reportCompare(simplified1.isGenerator(), true, "simplified case 1: is generator");
+reportCompare(typeof simplified1(), "object", "simplified case 1: calling doesn't crash");
+reportCompare(simplified2.isGenerator(), true, "simplified case 2: is generator");
+reportCompare(typeof simplified2(), "object", "simplified case 2: calling doesn't crash");