diff -r 000000000000 -r 6474c204b198 dom/workers/test/instanceof_worker.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/workers/test/instanceof_worker.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+onmessage = function(event) {
+  postMessage({event: "XMLHttpRequest",
+               status: (new XMLHttpRequest() instanceof XMLHttpRequest),
+               last: false });
+  postMessage({event: "XMLHttpRequestUpload",
+               status: ((new XMLHttpRequest()).upload instanceof XMLHttpRequestUpload),
+               last: true });
+}