Converting html before creating DOM Document.

Related to #3483397

src/Utility/KlaroHelper.php

@@ -597,11 +597,12 @@ class KlaroHelper {
     }
 
     $klaro_apps = $this->getApps();
-    $dom = new \DOMDocument();
+
     $complete_html = strpos($html, '<!DOCTYPE') !== FALSE;
     // If "complete html" is supplied use DomDocument to create.
     if ($complete_html) {
       $dom = new \DOMDocument();
+      $html = mb_encode_numericentity($html, [0x80, 0x10FFFF, 0, 0x1FFFFF], 'UTF-8');
       $dom->loadHTML($html, LIBXML_NOERROR | LIBXML_SCHEMA_CREATE);
     }
     else {
@@ -804,6 +805,7 @@ class KlaroHelper {
 
     if ($complete_html) {
       $html = $dom->saveHTML();
+      $html = mb_decode_numericentity($html, [0x80, 0x10FFFF, 0, 0x1FFFFF], 'UTF-8');
     }
     else {
       $html = Html::serialize($dom);