An event that typed code only listened to with a listener taking no
parameters had no bridge entry: the scan marked a listener as typed only
when one of its parameters was not a checked-dynamic value. Emitting the
event through an `any` reference then threw instead of calling the
listener. A TypeScript listener with no parameters now marks the event as
typed. A JavaScript function without parameters still registers as before,
since it can read `arguments`.
Chris Tate
cd38fd2248