diff --git src/wp-admin/includes/update-core.php src/wp-admin/includes/update-core.php
index 82903f76df..9f7889ac62 100644
--- src/wp-admin/includes/update-core.php
+++ src/wp-admin/includes/update-core.php
@@ -714,24 +714,35 @@ $_old_files = array(
 'wp-includes/js/tinymce/skins/lightgray/fonts/tinymce.json',
 'wp-includes/js/tinymce/skins/lightgray/skin.ie7.min.css',
 // 4.9
-'wp-includes/js/plupload/plupload.flash.swf',
-'wp-includes/js/plupload/plupload.silverlight.xap',
-'wp-includes/js/plupload/plupload.full.min.js',
-'wp-includes/js/swfupload/plugins',
-'wp-includes/js/swfupload/swfupload.swf',
-'wp-admin/css/press-this-editor.css',
 'wp-admin/css/press-this-editor-rtl.css',
 'wp-admin/css/press-this-editor-rtl.min.css',
+'wp-admin/css/press-this-editor.css',
 'wp-admin/css/press-this-editor.min.css',
-'wp-admin/css/press-this.css',
 'wp-admin/css/press-this-rtl.css',
 'wp-admin/css/press-this-rtl.min.css',
+'wp-admin/css/press-this.css',
 'wp-admin/css/press-this.min.css',
 'wp-admin/includes/class-wp-press-this.php',
-'wp-admin/js/press-this.js',
-'wp-admin/js/press-this.min.js',
 'wp-admin/js/bookmarklet.js',
 'wp-admin/js/bookmarklet.min.js',
+'wp-admin/js/press-this.js',
+'wp-admin/js/press-this.min.js',
+'wp-includes/js/mediaelement/background.png',
+'wp-includes/js/mediaelement/bigplay.png',
+'wp-includes/js/mediaelement/bigplay.svg',
+'wp-includes/js/mediaelement/controls.png',
+'wp-includes/js/mediaelement/controls.svg',
+'wp-includes/js/mediaelement/flashmediaelement.swf',
+'wp-includes/js/mediaelement/froogaloop.min.js',
+'wp-includes/js/mediaelement/jumpforward.png',
+'wp-includes/js/mediaelement/loading.gif',
+'wp-includes/js/mediaelement/silverlightmediaelement.xap',
+'wp-includes/js/mediaelement/skipback.png',
+'wp-includes/js/plupload/plupload.flash.swf',
+'wp-includes/js/plupload/plupload.full.min.js',
+'wp-includes/js/plupload/plupload.silverlight.xap',
+'wp-includes/js/swfupload/plugins',
+'wp-includes/js/swfupload/swfupload.swf',
 );
 
 /**