MDL-14898 upgraded html purifier to 3.1.0 in HEAD

lib/htmlpurifier/HTMLPurifier/AttrDef/HTML/Length.php

@@ -1,8 +1,5 @@
 <?php
 
-require_once 'HTMLPurifier/AttrDef.php';
-require_once 'HTMLPurifier/AttrDef/HTML/Pixels.php';
-
 /**
  * Validates the HTML type length (not to be confused with CSS's length).
  * 
@@ -13,7 +10,7 @@ require_once 'HTMLPurifier/AttrDef/HTML/Pixels.php';
 class HTMLPurifier_AttrDef_HTML_Length extends HTMLPurifier_AttrDef_HTML_Pixels
 {
     
-    function validate($string, $config, &$context) {
+    public function validate($string, $config, $context) {
         
         $string = trim($string);
         if ($string === '') return false;