Fix traceback when clicking on right sidebar unread counts numbers.

If you clicked on the unread counts span inside the right sidebar
links, e.target would not be the link itself but instead the count
span inside the link, so the extraction of the user's email address
was incorrect.

(imported from commit 559d93622078e4d909f60de794df3f039ea7e5f2)

zephyr/static/js/ui.js

@@ -1204,7 +1204,7 @@ $(function () {
     });
 
     $('#user_presences').on('click', 'a', function (e) {
-        var email = $(e.target).attr('data-email');
+        var email = $(e.target).closest('a').attr('data-email');
         narrow.by('pm-with', email, {trigger: 'presence list'});
         compose.start('private', {private_message_recipient: email,
                                   trigger: 'presence list'});