diff -r 000000000000 -r 6474c204b198 js/src/tests/ecma_2/shell.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/ecma_2/shell.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,18 @@
+/* -*- 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 TZ_DIFF = getTimeZoneDiff();
+
+/*
+ * Originally, the test suite used a hard-coded value TZ_DIFF = -8.
+ * But that was only valid for testers in the Pacific Standard Time Zone!
+ * We calculate the proper number dynamically for any tester. We just
+ * have to be careful to use a date not subject to Daylight Savings Time...
+ */
+function getTimeZoneDiff()
+{
+  return -((new Date(2000, 1, 1)).getTimezoneOffset())/60;
+}