| PASS event exists on window, which is initially set to undefined | |
| PASS window.event is only defined during dispatch | |
| PASS window.event is undefined if the target is in a shadow tree (event dispatched outside shadow tree) | |
| PASS window.event is undefined if the target is in a shadow tree (event dispatched inside shadow tree) | |
| PASS window.event is set to the current event during dispatch | |
| PASS window.event is set to the current event, which is the event passed to dispatch | |