Event: Fix #14544. Remove elem from event handle, close gh-1400.

This also reduces memory leaks if the element is removed without cleaning
events (e.g with native DOM operations).

Not pickable into the 1.x branch because oldIE still needs this.
Ajax: Fix #14424. Use ActiveX in IE9+ on local files, close gh-1434.

We can't feature detect ActiveX in IE11, but we can just call
it and catch whatever error occurs, then try normal XHR.