IE10+: fire pointerdown and pointerup on click

Calling `.click()` on IE10 doesn't emit an mspointerdown event, and similarly calling `.click()` on IE11 doesn't emit a pointerdown event.

I assume this is a webdriver problem but leadfoot is supposed to work around that.   Perhaps it's already firing mousedown/mouseup, but it would be good if it fired the pointer events too, since that's what actually happens when the user clicks on IE10+.

