diff -r 000000000000 -r 6474c204b198 toolkit/modules/Timer.jsm
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/modules/Timer.jsm	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,42 @@
+/* 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/. */
+
+"use strict";
+
+/**
+ * JS module implementation of nsIDOMJSWindow.setTimeout and clearTimeout.
+ */
+
+this.EXPORTED_SYMBOLS = ["setTimeout", "clearTimeout"];
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cu = Components.utils;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+
+// This gives us >=2^30 unique timer IDs, enough for 1 per ms for 12.4 days.
+let gNextTimeoutId = 1; // setTimeout must return a positive integer
+
+let gTimeoutTable = new Map(); // int -> nsITimer
+
+this.setTimeout = function setTimeout(aCallback, aMilliseconds) {
+  let id = gNextTimeoutId++;
+  let args = Array.slice(arguments, 2);
+  let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+  timer.initWithCallback(function setTimeout_timer() {
+    gTimeoutTable.delete(id);
+    aCallback.apply(null, args);
+  }, aMilliseconds, timer.TYPE_ONE_SHOT);
+
+  gTimeoutTable.set(id, timer);
+  return id;
+}
+
+this.clearTimeout = function clearTimeout(aId) {
+  if (gTimeoutTable.has(aId)) {
+    gTimeoutTable.get(aId).cancel();
+    gTimeoutTable.delete(aId);
+  }
+}