When using native DOM helpers with jQuery, some events are not handled correctly

I believe this effects 'mouseenter', 'mouseleave', 'pointerenter' , and 'pointerleave'.

The issue is that if jQuery is present, Ember's event dispatcher will use jQuery to manage events. This means if you have, for instance a `mouseEnter` handler, `on('mouseenter')` will be used. Due to historical reasons, jQuery will not actually watch for the real 'mouseenter' event but will watch for 'mouseover'.

If you are using `$(el).mouseenter()` jQuery will handle this correctly. However, if you transition to native DOM helpers and attempt to do `triggerEvent(el, 'mouseenter')` we will send only the 'mouseenter' event which the jQuery-backed event dispatcher will not recognize.

A temporary workaround in this case is `triggerEvent(el, 'mouseover')`.

Given that many people will probably be switching to native DOM helpers soon, we should consider whether anything should be done to account for this scenario.