diff -r 000000000000 -r 6474c204b198 dom/bindings/test/TestInterfaceJS.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/bindings/test/TestInterfaceJS.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,51 @@
+/* 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/. */
+
+const Cu = Components.utils;
+const Ci = Components.interfaces;
+
+"use strict";
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+
+var gGlobal = this;
+function checkGlobal(obj) {
+  if (Object(obj) === obj && Cu.getGlobalForObject(obj) != gGlobal) {
+    // This message may not make it to the caller in a useful form, so dump
+    // as well.
+    var msg = "TestInterfaceJS received an object from a different scope!";
+    dump(msg + "\n");
+    throw new Error(msg);
+  }
+}
+
+function TestInterfaceJS(anyArg, objectArg) {}
+
+TestInterfaceJS.prototype = {
+  classID: Components.ID("{2ac4e026-cf25-47d5-b067-78d553c3cad8}"),
+  contractID: "@mozilla.org/dom/test-interface-js;1",
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsISupports]),
+
+  __init: function (anyArg, objectArg) {
+    this._anyAttr = undefined;
+    this._objectAttr = null;
+    this._anyArg = anyArg;
+    this._objectArg = objectArg;
+    checkGlobal(anyArg);
+    checkGlobal(objectArg);
+  },
+
+  get anyArg() { return this._anyArg; },
+  get objectArg() { return this._objectArg; },
+  get anyAttr() { return this._anyAttr; },
+  set anyAttr(val) { checkGlobal(val); this._anyAttr = val; },
+  get objectAttr() { return this._objectAttr; },
+  set objectAttr(val) { checkGlobal(val); this._objectAttr = val; },
+  pingPongAny: function(any) { checkGlobal(any); return any; },
+  pingPongObject: function(obj) { checkGlobal(obj); return obj; },
+
+  getCallerPrincipal: function() { return Cu.getWebIDLCallerPrincipal().origin; }
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([TestInterfaceJS])