Update favcount.js to v1.4.0

Inspired by [meta/11825](https://meta.discourse.org/t/security-error-on-console-noticed-on-meta/11825) to bump [favcount](https://github.com/chrishunt/favcount) to the latest version.

There are no behavioral changes. This just adds a missing semicolon and allows customization of opacity and font, both of which have the same defaults.