fixup! Bug 19273: Avoid JavaScript patching of the external app helper dialog.

 * due to Firefox Bug https://bugzilla.mozilla.org/show_bug.cgi?id=440892

 *

 * An instance of this module is created each time the browser starts to

 * download a file that may be opened by another or application and when

 * an external application may be invoked to handle an URL (e.g., when the

 * user clicks on a mailto: URL).

 * download a file and when an external application may be invoked to

 * handle an URL (e.g., when the user clicks on a mailto: URL).

 *************************************************************************/

const Cc = Components.classes;