diff -r 000000000000 -r 6474c204b198 dom/workers/test/consoleReplaceable_worker.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/workers/test/consoleReplaceable_worker.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,10 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+onmessage = function(event) {
+  postMessage({event: 'console exists', status: !!console, last : false});
+  console = 42;
+  postMessage({event: 'console is replaceable', status: console === 42, last : true});
+}