Events -> Ready code not working on IE8

Hi there,

The "on load" callback wasn't getting run in my simple test and it was because `readyState` was straight to `complete` and there's no `interactive`. That's on IE8.

Be good to have some discussion regarding whether the callback could get called twice if `readyState` does get to `interactive` and then `complete`.  If yes, then we'd want to discuss the best code for this.