diff --git a/core/lib/Drupal/Component/Utility/Xss.php b/core/lib/Drupal/Component/Utility/Xss.php
index 8d0d257..4114ed9 100644
--- a/core/lib/Drupal/Component/Utility/Xss.php
+++ b/core/lib/Drupal/Component/Utility/Xss.php
@@ -22,6 +22,15 @@ class Xss {
   protected static $adminTags = array('a', 'abbr', 'acronym', 'address', 'article', 'aside', 'b', 'bdi', 'bdo', 'big', 'blockquote', 'br', 'caption', 'cite', 'code', 'col', 'colgroup', 'command', 'dd', 'del', 'details', 'dfn', 'div', 'dl', 'dt', 'em', 'figcaption', 'figure', 'footer', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'header', 'hgroup', 'hr', 'i', 'img', 'ins', 'kbd', 'li', 'mark', 'menu', 'meter', 'nav', 'ol', 'output', 'p', 'pre', 'progress', 'q', 'rp', 'rt', 'ruby', 's', 'samp', 'section', 'small', 'span', 'strong', 'sub', 'summary', 'sup', 'table', 'tbody', 'td', 'tfoot', 'th', 'thead', 'time', 'tr', 'tt', 'u', 'ul', 'var', 'wbr');
 
   /**
+   * The list of html tags to allow for a given filter operation.
+   *
+   * @var array
+   *
+   * @see \Drupal\Component\Utility\Xss::split()
+   */
+  protected static $allowedTags = array('a', 'em', 'strong', 'cite', 'blockquote', 'code', 'ul', 'ol', 'li', 'dl', 'dt', 'dd');
+
+  /**
    * Filters HTML to prevent cross-site-scripting (XSS) vulnerabilities.
    *
    * Based on kses by Ulf Harnhammar, see http://sourceforge.net/projects/kses.
@@ -55,7 +64,7 @@ public static function filter($string, $allowed_tags = array('a', 'em', 'strong'
       return '';
     }
     // Store the text format.
-    static::split($allowed_tags, TRUE);
+    static::$allowedTags = $allowed_tags;
     // Remove NULL characters (ignored by some browsers).
     $string = str_replace(chr(0), '', $string);
     // Remove Netscape 4 JS entities.
@@ -107,26 +116,14 @@ public static function filterAdmin($string) {
    * Processes an HTML tag.
    *
    * @param array $matches
-   *   An array with various meaning depending on the value of $store.
-   *   If $store is TRUE then the array contains the allowed tags.
-   *   If $store is FALSE then the array has one element, the HTML tag to process.
-   * @param bool $store
-   *   Whether to store $m.
+   *   An array containing a single HTML tag to process.
    *
    * @return string
    *   If the element isn't allowed, an empty string. Otherwise, the cleaned up
    *   version of the HTML element.
    */
-  protected static function split($matches, $store = FALSE) {
-    static $allowed_html;
-
-    if ($store) {
-      $allowed_html = array_flip($matches);
-      return;
-    }
-
-    $string = $matches[1];
-
+  protected static function split(array $matches) {
+    $string = $matches[0];
     if (substr($string, 0, 1) != '<') {
       // We matched a lone ">" character.
       return '&gt;';
@@ -150,7 +147,7 @@ protected static function split($matches, $store = FALSE) {
       $elem = '!--';
     }
 
-    if (!isset($allowed_html[strtolower($elem)])) {
+    if (!isset(static::$allowedTags[strtolower($elem)])) {
       // Disallowed HTML element.
       return '';
     }