Ignore case differences when checking file extension in wp_audio_shortcode() and wp_video_shortcode(). props nofearinc, bhengh. fixes #25140.
Built from https://develop.svn.wordpress.org/trunk@25128


git-svn-id: https://core.svn.wordpress.org/trunk@25108 1a063a9b-81f0-0310-95a4-ce76da25c4cd