Media: Remove inline scripts targeting IE < 9.

In #24902, an inline script was introduced to `wp_playlist_scripts()`, `wp_audio_shortcode()`, and `wp_video_shortcode()` for HTML5 compatibility in browsers running IE 8 and earlier.

These browsers have long been unsupported by WordPress, and unsupported by Microsoft for 9 years or more. So this compatibility code is no longer necessary and can safely be removed.

Hit the road, Jack, and don't ya come back no more, no more, no more, no more!

Props aslamdoctor, mindctrl, nigelnelles, joedolson.
Fixes #63471.

git-svn-id: https://develop.svn.wordpress.org/trunk@60285 602fd350-edb4-49c9-b593-d223f7449a82

Author: desrosj

src/wp-includes/media.php

@@ -2992,9 +2992,6 @@ function wp_underscore_playlist_templates() {
 function wp_playlist_scripts( $type ) {
 	wp_enqueue_style( 'wp-mediaelement' );
 	wp_enqueue_script( 'wp-playlist' );
-	?>
-<!--[if lt IE 9]><script>document.createElement('<?php echo esc_js( $type ); ?>');</script><![endif]-->
-	<?php
 	add_action( 'wp_footer', 'wp_underscore_playlist_templates', 0 );
 	add_action( 'admin_footer', 'wp_underscore_playlist_templates', 0 );
 }
@@ -3502,14 +3499,7 @@ function wp_audio_shortcode( $attr, $content = '' ) {
 		}
 	}
 
-	$html = '';
-
-	if ( 'mediaelement' === $library && 1 === $instance ) {
-		$html .= "<!--[if lt IE 9]><script>document.createElement('audio');</script><![endif]-->\n";
-	}
-
-	$html .= sprintf( '<audio %s controls="controls">', implode( ' ', $attr_strings ) );
-
+	$html    = sprintf( '<audio %s controls="controls">', implode( ' ', $attr_strings ) );
 	$fileurl = '';
 	$source  = '<source type="%s" src="%s" />';
 
@@ -3787,14 +3777,7 @@ function wp_video_shortcode( $attr, $content = '' ) {
 		}
 	}
 
-	$html = '';
-
-	if ( 'mediaelement' === $library && 1 === $instance ) {
-		$html .= "<!--[if lt IE 9]><script>document.createElement('video');</script><![endif]-->\n";
-	}
-
-	$html .= sprintf( '<video %s controls="controls">', implode( ' ', $attr_strings ) );
-
+	$html    = sprintf( '<video %s controls="controls">', implode( ' ', $attr_strings ) );
 	$fileurl = '';
 	$source  = '<source type="%s" src="%s" />';
 

tests/phpunit/tests/media.php

@@ -999,7 +999,6 @@ public function test_video_shortcode_body() {
 		$content = apply_filters( 'the_content', $video );
 
 		$expected = '<div style="width: ' . $width . 'px;" class="wp-video">' .
-			"<!--[if lt IE 9]><script>document.createElement('video');</script><![endif]-->\n" .
 			'<video class="wp-video-shortcode" id="video-' . $post_id . '-1" width="' . $width . '" height="' . $h . '" preload="metadata" controls="controls">' .
 			'<source type="video/mp4" src="http://domain.tld/wp-content/uploads/2013/12/xyz.mp4?_=1" />' .
 			'<!-- WebM/VP8 for Firefox4, Opera, and Chrome --><source type="video/webm" src="myvideo.webm" />' .