IETF language changes in MediaElement:

https://github.com/johndyer/mediaelement/pull/1270/

Reverts [28801].
Fixes #29182.


git-svn-id: https://develop.svn.wordpress.org/trunk@30637 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/script-loader.php

@@ -308,7 +308,7 @@ function wp_default_scripts( &$scripts ) {
 
 	$scripts->add( 'mediaelement', "/wp-includes/js/mediaelement/mediaelement-and-player.min.js", array('jquery'), '2.15.1', 1 );
 	did_action( 'init' ) && $scripts->localize( 'mediaelement', 'mejsL10n', array(
-		'language' => substr( get_bloginfo( 'language' ), 0, 2 ),
+		'language' => get_bloginfo( 'language' ),
 		'strings'  => array(
 			'Close'               => __( 'Close' ),
 			'Fullscreen'          => __( 'Fullscreen' ),