The Tor Browser / file revision

 function sbTest() {

   var threw = false;

   try {

     for (var x in Components) { }

     do_check_true(false, "Shouldn't be able to enumerate Components");

   } catch(e) {

     do_check_true(true, "Threw appropriately");

     threw = true;

   }

   do_check_true(threw, "Shouldn't have thrown uncatchable exception");

 }

 function run_test() {

   var sb = Components.utils.Sandbox('http://www.example.com', { wantComponents: true });

   sb.do_check_true = do_check_true;

   Components.utils.evalInSandbox(sbTest.toSource(), sb);

   Components.utils.evalInSandbox('sbTest();', sb);

 }