diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_5/Regress/regress-254296.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_5/Regress/regress-254296.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,26 @@
+/* -*- 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 = 254296;
+var summary = 'javascript regular expression negative lookahead';
+var actual = '';
+var expect = '';
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+
+expect = [3].toString();
+actual = /^\d(?!\.\d)/.exec('3.A');
+if (actual)
+{
+  actual = actual.toString();
+}
+ 
+reportCompare(expect, actual, summary + ' ' + inSection(1));
+
+expect = 'AB';
+actual = /(?!AB+D)AB/.exec("AB") + '';
+reportCompare(expect, actual, summary + ' ' + inSection(2));