diff -r 000000000000 -r 6474c204b198 js/src/tests/ecma_3/String/regress-313567.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/ecma_3/String/regress-313567.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,23 @@
+/* -*- 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 = 313567;
+var summary = 'String.prototype.length should not be generic';
+var actual = '';
+var expect = '';
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+
+var s = new String("1");
+s.toString = function() {
+  return "22";
+}
+  var expect = 1;
+var actual = s.length;
+printStatus("expect="+expect+" actual="+actual);
+ 
+reportCompare(expect, actual, summary);