Executes the subscription callback, passing the firing arguments as the
first parameters to that callback. For events that are configured with
emitFacade=true, it is common practice to pass the triggering DOMEventFacade
as the first parameter. Barring a proper DOMEventFacade or EventFacade
(from a CustomEvent), a new EventFacade will be generated. In that case, if
fire() is called with a simple object, it will be mixed into the facade.
Otherwise, the facade will be prepended to the callback parameters.
For notifiers provided to delegate logic, the first argument should be an
object with a "currentTarget" property to identify what object to
default as 'this' in the callback. Typically this is gleaned from the
DOMEventFacade or EventFacade, but if configured with emitFacade=false, an
object must be provided. In that case, the object will be removed from the
callback parameters.
Additional arguments passed during event subscription will be
automatically added after those passed to fire().