Fixes T4586, where a keystroke like "return" to submit a form could remove DOM nodes rendering a tooltip, leaving the user with a permanent phantom tooltip.

(@spicyj, if you come up with anything better than this feel free to send a followup, but I think this is a reasonable fix.)

A nice side effect of this is that it hides any tooltips obscuring a text input when you start typing.

Hovered over a tooltip, pressed a key, tip vanished.