js: Use ES6 object literal shorthand syntax.

Generated by ESLint.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

static/js/user_status.js

@@ -9,7 +9,7 @@ exports.server_update = function (opts) {
             status_text: opts.status_text,
         },
         idempotent: true,
-        success: function () {
+        success() {
             if (opts.success) {
                 opts.success();
             }