Arrow Keydown event triggers click event for all [role="menu]

Created by: chamelea

I am writing my own aria menu object and handling the document click event differently than the document arrow keydown event. I was surprised when dropdown.js actually triggered a click event when I used the down arrow.

See: https://github.com/twbs/bootstrap/blob/master/js/dropdown.js#L158 https://github.com/twbs/bootstrap/blob/master/js/dropdown.js#L72