The Tor Browser / file revision

 const RELATIVE_DIR = "image/test/browser/";

 const TESTROOT = "http://example.com/browser/" + RELATIVE_DIR;

 const TESTROOT2 = "http://example.org/browser/" + RELATIVE_DIR;

 var chrome_root = getRootDirectory(gTestPath);

 const CHROMEROOT = chrome_root;

 function getImageLoading(doc, id) {

   var htmlImg = doc.getElementById(id);

   return htmlImg.QueryInterface(Ci.nsIImageLoadingContent);

 }

 // Tries to get the Moz debug image, imgIContainerDebug. Only works

 // in a debug build. If we succeed, we call func().

 function actOnMozImage(doc, id, func) {

   var imgContainer = getImageLoading(doc, id).getRequest(Ci.nsIImageLoadingContent.CURRENT_REQUEST).image;

   var mozImage;

   try {

     mozImage = imgContainer.QueryInterface(Ci.imgIContainerDebug);

   }

   catch (e) {

     return false;

   }

   func(mozImage);

   return true;

 }