fix: Don't disable mouse hover UI functionality on touch screens (#5433)

Because devices can have both touch and mouse input.

ietf/static/js/ietf.js

@@ -141,11 +141,9 @@ $(document)
                     attachTo.append(menu.join(""));
                 }
 
-                if (!("ontouchstart" in document.documentElement)) {
                 $("ul.nav li.dropdown, ul.nav li.dropend")
                     .on("mouseenter mouseleave", dropdown_hover);
             }
-            }
         });
     });