diff -r 000000000000 -r 6474c204b198 js/src/jit-test/lib/string.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/lib/string.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,24 @@
+/* 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/. */
+
+
+if (typeof isHighSurrogate === 'undefined') {
+    var isHighSurrogate = function isHighSurrogate(s) {
+        var c = s.charCodeAt(0);
+        return c >= 0xD800 && c <= 0xDBFF;
+    }
+}
+
+if (typeof isLowSurrogate === 'undefined') {
+    var isLowSurrogate = function isLowSurrogate(s) {
+        var c = s.charCodeAt(0);
+        return c >= 0xDC00 && c <= 0xDFFF;
+    }
+}
+
+if (typeof isSurrogatePair === 'undefined') {
+    var isSurrogatePair = function isSurrogatePair(s) {
+        return s.length == 2 && isHighSurrogate(s[0]) && isLowSurrogate(s[1]);
+    }
+}