Make sure that mousing over Chrome "internal div" elements results in no...

Make sure that mousing over Chrome "internal div" elements results in no trigger of a mouseleave. Fixes #8209.

src/event.js

@@ -652,13 +652,15 @@ var withinElement = function( event ) {
 
 	// Firefox sometimes assigns relatedTarget a XUL element
 	// which we cannot access the parentNode property of
+	// Chrome does something similar, the parentNode property
+	// can be accessed but is null.
 	try {
 		// Traverse up the tree
 		while ( parent && parent !== this ) {
 			parent = parent.parentNode;
 		}
 
-		if ( parent !== this ) {
+		if ( parent && parent !== this ) {
 			// set the correct event type
 			event.type = event.data;