The Tor Browser / file revision

 function test() {

   waitForExplicitFinish(); 

   var newTab;

   var newBrowser;

   const secMan = Cc["@mozilla.org/scriptsecuritymanager;1"].getService(Ci.nsIScriptSecurityManager);

   function testLoad(event) {

     newBrowser.removeEventListener("load", testLoad, true);

     is (event.target, newBrowser.contentDocument, "Unexpected target");

     var prin = newBrowser.contentDocument.nodePrincipal;

     isnot(prin, null, "Loaded principal must not be null");

     isnot(prin, undefined, "Loaded principal must not be undefined");

     is(secMan.isSystemPrincipal(prin), false,

        "Loaded principal must not be system");

     gBrowser.removeTab(newTab);

     finish();

   }

   newTab = gBrowser.addTab();

   newBrowser = gBrowser.getBrowserForTab(newTab);

   newBrowser.contentWindow.location.href = "about:blank"

   newBrowser.addEventListener("load", testLoad, true);

 }