diff -r 000000000000 -r 6474c204b198 browser/devtools/tilt/test/browser_tilt_utils03.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/tilt/test/browser_tilt_utils03.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,18 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+function test() {
+  let dom = TiltUtils.DOM;
+
+  is(dom.parentNode, null,
+    "The parent node should not be initially set.");
+
+  dom.parentNode = {};
+  ok(dom.parentNode,
+    "The parent node should now be set.");
+
+  TiltUtils.clearCache();
+  is(dom.parentNode, null,
+    "The parent node should not be set after clearing the cache.");
+}