diff -r 000000000000 -r 6474c204b198 dom/workers/test/jsversion_worker.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/workers/test/jsversion_worker.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,14 @@
+onmessage = function(evt) {
+  if (evt.data != 0) {
+    var worker = new Worker('jsversion_worker.js');
+    worker.onmessage = function(evt) {
+      postMessage(evt.data);
+    }
+
+    worker.postMessage(evt.data - 1);
+    return;
+  }
+
+  let foo = 'bar';
+  postMessage(true);
+}