Tweak for r39314: don't add a line break before the "Go" button on the watchlist...

Tweak for r39314: don't add a line break before the "Go" button on the watchlist.  This used up yet more vertical space.  It also visually dissociated the "Go" button from the namespace selector, making it look like it maybe applied to all the buttons above too, due to lack of a fieldset.  On the other hand, this way looks a little awkward too.  Maybe there's a better way?

Reported by User:Garion96 on [[WP:VPT]]: <http://en.wikipedia.org/w/index.php?title=Wikipedia:Village_pump_(technical)&oldid=233532922#.22go.22_button_in_watchlist>