jquery: add second signature for triggerHandler.

This one takes an event instead of an event type. See documentation
(http://api.jquery.com/triggerHandler/) and related documentation
ticket (https://github.com/jquery/api.jquery.com/issues/393).

jquery/jquery.d.ts

@@ -2455,6 +2455,14 @@ interface JQuery {
      */
     triggerHandler(eventType: string, ...extraParameters: any[]): Object;
 
+    /**
+     * Execute all handlers attached to an element for an event.
+     * 
+     * @param event A jQuery.Event object.
+     * @param extraParameters An array of additional parameters to pass along to the event handler.
+     */
+    triggerHandler(event: JQueryEventObject, ...extraParameters: any[]): Object;
+
     /**
      * Remove a previously-attached event handler from the elements.
      *