Make sure that the correct type is set for live mouseenter/mouseleave events. Fixes #6169.

src/event.js

@@ -1022,6 +1022,7 @@ function liveHandler( event ) {
 
 				// Those two events require additional checking
 				if ( handleObj.preType === "mouseenter" || handleObj.preType === "mouseleave" ) {
+					event.type = handleObj.preType;
 					related = jQuery( event.relatedTarget ).closest( handleObj.selector )[0];
 				}