diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_5/Regress/regress-274035.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_5/Regress/regress-274035.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,29 @@
+/* -*- 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 = 274035;
+var summary = 'Array.prototype[concat|slice|splice] lengths';
+var actual = '';
+var expect = '';
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+
+status = summary + ' ' + inSection(1) + ' Array.prototype.concat.length ';
+expect = 1;
+actual   = Array.prototype.concat.length;
+reportCompare(expect, actual, status);
+
+status = summary + ' ' + inSection(2) + ' Array.prototype.slice.length ';
+expect = 2;
+actual   = Array.prototype.slice.length;
+reportCompare(expect, actual, status);
+
+status = summary + ' ' + inSection(3) + ' Array.prototype.splice.length ';
+expect = 2;
+actual   = Array.prototype.splice.length;
+reportCompare(expect, actual, status);
+