Bug 722479 - browser/components/thumbnails/test/ tests leak chrome://global/content/mozilla.xhtml; r=dao

browser/components/thumbnails/test/head.js

@@ -9,6 +9,8 @@ let PageThumbsCache = tmp.PageThumbsCache;
 registerCleanupFunction(function () {
   while (gBrowser.tabs.length > 1)
     gBrowser.removeTab(gBrowser.tabs[1]);
+
+  cachedXULDocument = null;
 });
 
 let cachedXULDocument;
@@ -144,6 +146,7 @@ function getXULDocument(aCallback) {
 
   iframe.addEventListener("DOMContentLoaded", function onLoad() {
     iframe.removeEventListener("DOMContentLoaded", onLoad, false);
+    doc.body.removeChild(iframe);
     aCallback(cachedXULDocument = iframe.contentDocument);
   }, false);