It looks like Facebook has updated the location of their script. You can easily update it in the code. Instead of:
<script src="http://connect.facebook.net/en_US/all.js#xfbml=1"></script>
use:
<script async defer crossorigin="anonymous" src="https://connect.facebook.net/en_US/sdk.js#xfbml=1&version=v14.0"></script>