MDL-14898 upgraded html purifier to 3.1.0 in HEAD

lib/htmlpurifier/HTMLPurifier/Token/End.php

@@ -0,0 +1,13 @@
+<?php
+
+/**
+ * Concrete end token class.
+ * 
+ * @warning This class accepts attributes even though end tags cannot. This
+ * is for optimization reasons, as under normal circumstances, the Lexers
+ * do not pass attributes.
+ */
+class HTMLPurifier_Token_End extends HTMLPurifier_Token_Tag
+{
+    
+}