diff -r 000000000000 -r 6474c204b198 js/src/builtin/Date.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/builtin/Date.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,119 @@
+/* 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/. */
+
+/*global intl_DateTimeFormat: false, */
+
+
+var dateTimeFormatCache = new Record();
+
+
+/**
+ * Format this Date object into a date and time string, using the locale and
+ * formatting options provided.
+ *
+ * Spec: ECMAScript Language Specification, 5.1 edition, 15.9.5.5.
+ * Spec: ECMAScript Internationalization API Specification, 13.3.1.
+ */
+function Date_toLocaleString() {
+    // Steps 1-2.  Note that valueOf enforces "this time value" restrictions.
+    var x = callFunction(std_Date_valueOf, this);
+    if (std_isNaN(x))
+        return "Invalid Date";
+
+    // Steps 3-4.
+    var locales = arguments.length > 0 ? arguments[0] : undefined;
+    var options = arguments.length > 1 ? arguments[1] : undefined;
+
+    // Step 5-6.
+    var dateTimeFormat;
+    if (locales === undefined && options === undefined) {
+        // This cache only optimizes for the old ES5 toLocaleString without
+        // locales and options.
+        if (dateTimeFormatCache.dateTimeFormat === undefined) {
+            options = ToDateTimeOptions(options, "any", "all");
+            dateTimeFormatCache.dateTimeFormat = intl_DateTimeFormat(locales, options);
+        }
+        dateTimeFormat = dateTimeFormatCache.dateTimeFormat;
+    } else {
+        options = ToDateTimeOptions(options, "any", "all");
+        dateTimeFormat = intl_DateTimeFormat(locales, options);
+    }
+
+    // Step 7.
+    return intl_FormatDateTime(dateTimeFormat, x);
+}
+
+
+/**
+ * Format this Date object into a date string, using the locale and formatting
+ * options provided.
+ *
+ * Spec: ECMAScript Language Specification, 5.1 edition, 15.9.5.6.
+ * Spec: ECMAScript Internationalization API Specification, 13.3.2.
+ */
+function Date_toLocaleDateString() {
+    // Steps 1-2.  Note that valueOf enforces "this time value" restrictions.
+    var x = callFunction(std_Date_valueOf, this);
+    if (std_isNaN(x))
+        return "Invalid Date";
+
+    // Steps 3-4.
+    var locales = arguments.length > 0 ? arguments[0] : undefined;
+    var options = arguments.length > 1 ? arguments[1] : undefined;
+
+    // Step 5-6.
+    var dateTimeFormat;
+    if (locales === undefined && options === undefined) {
+        // This cache only optimizes for the old ES5 toLocaleDateString without
+        // locales and options.
+        if (dateTimeFormatCache.dateFormat === undefined) {
+            options = ToDateTimeOptions(options, "date", "date");
+            dateTimeFormatCache.dateFormat = intl_DateTimeFormat(locales, options);
+        }
+        dateTimeFormat = dateTimeFormatCache.dateFormat;
+    } else {
+        options = ToDateTimeOptions(options, "date", "date");
+        dateTimeFormat = intl_DateTimeFormat(locales, options);
+    }
+
+    // Step 7.
+    return intl_FormatDateTime(dateTimeFormat, x);
+}
+
+
+/**
+ * Format this Date object into a time string, using the locale and formatting
+ * options provided.
+ *
+ * Spec: ECMAScript Language Specification, 5.1 edition, 15.9.5.7.
+ * Spec: ECMAScript Internationalization API Specification, 13.3.3.
+ */
+function Date_toLocaleTimeString() {
+    // Steps 1-2.  Note that valueOf enforces "this time value" restrictions.
+    var x = callFunction(std_Date_valueOf, this);
+    if (std_isNaN(x))
+        return "Invalid Date";
+
+    // Steps 3-4.
+    var locales = arguments.length > 0 ? arguments[0] : undefined;
+    var options = arguments.length > 1 ? arguments[1] : undefined;
+
+    // Step 5-6.
+    var dateTimeFormat;
+    if (locales === undefined && options === undefined) {
+        // This cache only optimizes for the old ES5 toLocaleTimeString without
+        // locales and options.
+        if (dateTimeFormatCache.timeFormat === undefined) {
+            options = ToDateTimeOptions(options, "time", "time");
+            dateTimeFormatCache.timeFormat = intl_DateTimeFormat(locales, options);
+        }
+        dateTimeFormat = dateTimeFormatCache.timeFormat;
+    } else {
+        options = ToDateTimeOptions(options, "time", "time");
+        dateTimeFormat = intl_DateTimeFormat(locales, options);
+    }
+
+    // Step 7.
+    return intl_FormatDateTime(dateTimeFormat, x);
+}