Missing cache tags for Superfish block

There are no menu item cache tags applied to Superfish for Drupal 8.

Steps to reproduce

1. Turn on internal page cache, internal dynamic page cache modules. These should be on at all times anyway.
2. Add a Superfish block as normal
3. Add a menu item title.
4. Edit the menu item title.
5. Result: the menu item is not changed.

You can see core's menu block adding its cache tags in MenuLinkTree::build() / $tree_cacheability