Change design of compose form in web UI (#28119)

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/mastodon/components/dropdown_menu.jsx

@@ -165,7 +165,7 @@ class Dropdown extends PureComponent {
     children: PropTypes.node,
     icon: PropTypes.string,
     iconComponent: PropTypes.func,
-    items: PropTypes.oneOfType([PropTypes.array, ImmutablePropTypes.list]).isRequired,
+    items: PropTypes.oneOfType([PropTypes.array, ImmutablePropTypes.list]),
     loading: PropTypes.bool,
     size: PropTypes.number,
     title: PropTypes.string,