var temporaryDirectory = Components.classes["@mozilla.org/file/directory_service;1"].getService(Components.interfaces.nsIProperties).get("TmpD", Components.interfaces.nsIFile);
// If the temporary directory exists, is a directory and is writable
var converter = Components.classes["@mozilla.org/intl/scriptableunicodeconverter"].createInstance(Components.interfaces.nsIScriptableUnicodeConverter);
var htmlText = null;
var inputStream = Components.classes["@mozilla.org/network/file-input-stream;1"].createInstance(Components.interfaces.nsIFileInputStream);
var scriptableStream = Components.classes["@mozilla.org/scriptableinputstream;1"].createInstance(Components.interfaces.nsIScriptableInputStream);