The wrapper div might have had some functionality in the far past (cross-browser rendering?), it's simply unnecessary back to IE 7 at least, as the ul itself is able to be positioned equally.
Current source:
<div class="menu"> <ul> <li id="ca-move"><a href="/wiki/Special:MovePage/Front_end" title="Rename this page [ctrl-option-m]" accesskey="m">Move</a></li> </ul> </div>
Expected source
<ul class="menu"> <li id="ca-move"><a href="/wiki/Special:MovePage/Front_end" title="Rename this page [ctrl-option-m]" accesskey="m">Move</a></li> </ul>