rem: var uri = Components.classes["@mozilla.org/network/io-service;1"] .getService(Components.interfaces.nsIIOService) .newFileURI(aFile); 
add: var uri = Cc["@mozilla.org/network/io-service;1"]. getService(Ci.nsIIOService).newFileURI(aFile); 
context: function openExternal(aFile){  var uri = Components.classes["@mozilla.org/network/io-service;1"]                      .getService(Components.interfaces.nsIIOService)                      .newFileURI(aFile);  var protocolSvc =       Components.classes["@mozilla.org/uriloader/external-protocol-service;1"]                .getService(Components.interfaces.nsIExternalProtocolService);  protocolSvc.loadUrl(uri);  return;}
meta: 10520	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/10520/c816c402c2dc9a4ba3e0172325a9186da0704138/downloads.js/buggy/toolkit/mozapps/downloads/content/downloads.js