The jQuery `hasClass` method accepts a class name without a prefix '.' (period). Remove an errant class name with a '.' in `wp-mediaelement.js` that broke the selector in certain circumstances.
Props kostasx, Presskopp.
Fixes#40354.
git-svn-id: https://develop.svn.wordpress.org/trunk@40659 602fd350-edb4-49c9-b593-d223f7449a82