Dropdown pane: data-allow-overlap=false not respected

If a dropdown pane is larger than the browser window, the pane is not resized to respect window width. (data-allow-overlap=false is default according to [docs](http://foundation.zurb.com/sites/docs/dropdown.html#js-options))

FD 6.4.1

Testing: Resize browser window on CodePen to smaller than the large dropdown pane and refresh:
https://codepen.io/bwy/pen/GvJyqJ