The Tor Browser / file revision

 this.EXPORTED_SYMBOLS = ["Test"];

 this.Test = {

   start: function(ok, is, finish) {

     let worker = new ChromeWorker("jsm_url_worker.js");

     worker.onmessage = function(event) {

       if (event.data.type == 'finish') {

         finish();

       } else if (event.data.type == 'status') {

         ok(event.data.status, event.data.msg);

       } else if (event.data.type == 'url') {

         var xhr = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]

                   .createInstance(Components.interfaces.nsIXMLHttpRequest);

         xhr.open('GET', event.data.url, false);

         xhr.onreadystatechange = function() {

           if (xhr.readyState == 4) {

             ok(true, "Blob readable!");

           }

         }

         xhr.send();

       }

     };

     var self = this;

     worker.onerror = function(event) {

       is(event.target, worker);

       ok(false, "Worker had an error: " + event.data);

       self.worker.terminate();

       finish();

     };

     worker.postMessage(0);

   }

 };