diff -r c7c34916027a -r 177826044cd9 wp/wp-admin/async-upload.php
--- a/wp/wp-admin/async-upload.php	Mon Oct 14 18:06:33 2019 +0200
+++ b/wp/wp-admin/async-upload.php	Mon Oct 14 18:28:13 2019 +0200
@@ -22,7 +22,7 @@
 
 require_once( ABSPATH . 'wp-admin/admin.php' );
 
-header( 'Content-Type: text/html; charset=' . get_option( 'blog_charset' ) );
+header( 'Content-Type: text/plain; charset=' . get_option( 'blog_charset' ) );
 
 if ( isset( $_REQUEST['action'] ) && 'upload-attachment' === $_REQUEST['action'] ) {
 	include( ABSPATH . 'wp-admin/includes/ajax-actions.php' );
@@ -39,51 +39,61 @@
 }
 
 // just fetch the detail form for that attachment
-if ( isset($_REQUEST['attachment_id']) && ($id = intval($_REQUEST['attachment_id'])) && $_REQUEST['fetch'] ) {
+if ( isset( $_REQUEST['attachment_id'] ) && ( $id = intval( $_REQUEST['attachment_id'] ) ) && $_REQUEST['fetch'] ) {
 	$post = get_post( $id );
-	if ( 'attachment' != $post->post_type )
+	if ( 'attachment' != $post->post_type ) {
 		wp_die( __( 'Invalid post type.' ) );
-	if ( ! current_user_can( 'edit_post', $id ) )
+	}
+	if ( ! current_user_can( 'edit_post', $id ) ) {
 		wp_die( __( 'Sorry, you are not allowed to edit this item.' ) );
+	}
 
 	switch ( $_REQUEST['fetch'] ) {
-		case 3 :
-			if ( $thumb_url = wp_get_attachment_image_src( $id, 'thumbnail', true ) )
+		case 3:
+			if ( $thumb_url = wp_get_attachment_image_src( $id, 'thumbnail', true ) ) {
 				echo '<img class="pinkynail" src="' . esc_url( $thumb_url[0] ) . '" alt="" />';
+			}
 			echo '<a class="edit-attachment" href="' . esc_url( get_edit_post_link( $id ) ) . '" target="_blank">' . _x( 'Edit', 'media item' ) . '</a>';
 
 			// Title shouldn't ever be empty, but use filename just in case.
-			$file = get_attached_file( $post->ID );
+			$file  = get_attached_file( $post->ID );
 			$title = $post->post_title ? $post->post_title : wp_basename( $file );
 			echo '<div class="filename new"><span class="title">' . esc_html( wp_html_excerpt( $title, 60, '&hellip;' ) ) . '</span></div>';
 			break;
-		case 2 :
-			add_filter('attachment_fields_to_edit', 'media_single_attachment_fields_to_edit', 10, 2);
-			echo get_media_item($id, array( 'send' => false, 'delete' => true ));
+		case 2:
+			add_filter( 'attachment_fields_to_edit', 'media_single_attachment_fields_to_edit', 10, 2 );
+			echo get_media_item(
+				$id,
+				array(
+					'send'   => false,
+					'delete' => true,
+				)
+			);
 			break;
 		default:
-			add_filter('attachment_fields_to_edit', 'media_post_single_attachment_fields_to_edit', 10, 2);
-			echo get_media_item($id);
+			add_filter( 'attachment_fields_to_edit', 'media_post_single_attachment_fields_to_edit', 10, 2 );
+			echo get_media_item( $id );
 			break;
 	}
 	exit;
 }
 
-check_admin_referer('media-form');
+check_admin_referer( 'media-form' );
 
 $post_id = 0;
 if ( isset( $_REQUEST['post_id'] ) ) {
 	$post_id = absint( $_REQUEST['post_id'] );
-	if ( ! get_post( $post_id ) || ! current_user_can( 'edit_post', $post_id ) )
+	if ( ! get_post( $post_id ) || ! current_user_can( 'edit_post', $post_id ) ) {
 		$post_id = 0;
+	}
 }
 
 $id = media_handle_upload( 'async-upload', $post_id );
-if ( is_wp_error($id) ) {
+if ( is_wp_error( $id ) ) {
 	echo '<div class="error-div error">
-	<a class="dismiss" href="#" onclick="jQuery(this).parents(\'div.media-item\').slideUp(200, function(){jQuery(this).remove();});">' . __('Dismiss') . '</a>
-	<strong>' . sprintf(__('&#8220;%s&#8221; has failed to upload.'), esc_html($_FILES['async-upload']['name']) ) . '</strong><br />' .
-	esc_html($id->get_error_message()) . '</div>';
+	<button type="button" class="dismiss button-link" onclick="jQuery(this).parents(\'div.media-item\').slideUp(200, function(){jQuery(this).remove();});">' . __( 'Dismiss' ) . '</button>
+	<strong>' . sprintf( __( '&#8220;%s&#8221; has failed to upload.' ), esc_html( $_FILES['async-upload']['name'] ) ) . '</strong><br />' .
+	esc_html( $id->get_error_message() ) . '</div>';
 	exit;
 }
 
@@ -91,7 +101,7 @@
 	// Short form response - attachment ID only.
 	echo $id;
 } else {
-	// Long form response - big chunk o html.
+	// Long form response - big chunk of html.
 	$type = $_REQUEST['type'];
 
 	/**