mouseenter and mouseleave don't call listener #9
Description
For some reason 'mouseenter' and 'mouseleave' don't fire their listeners.
In the following example in chrome only el.addEventListener fires.
on( el, 'mouseenter', function() {
console.log( 'dom-event' );
});
el.addEventListener( 'mouseenter', function() {
console.log( 'addEventListener' );
});