The Tor Browser / file revision

 var reader = new FileReaderSync();

 /**

  * Expects an object containing a file and an encoding then uses a

  * FileReaderSync to read the file. Returns an object containing the

  * file read a binary string, text, url and ArrayBuffer.

  */

 onmessage = function(event) {

   var file = event.data.file;

   var encoding = event.data.encoding;

   var rtnObj = new Object();

   if (encoding != undefined) {

     rtnObj.text = reader.readAsText(file, encoding);

   } else {

     rtnObj.text = reader.readAsText(file);

   }

   rtnObj.bin = reader.readAsBinaryString(file);

   rtnObj.url = reader.readAsDataURL(file);

   rtnObj.arrayBuffer = reader.readAsArrayBuffer(file);

   postMessage(rtnObj);

 };