Added HTML Purifier 4.8.0 library using standard location

sites/all/libraries/htmlpurifier/HTMLPurifier/ChildDef/Optional.php

@@ -0,0 +1,45 @@
+<?php
+
+/**
+ * Definition that allows a set of elements, and allows no children.
+ * @note This is a hack to reuse code from HTMLPurifier_ChildDef_Required,
+ *       really, one shouldn't inherit from the other.  Only altered behavior
+ *       is to overload a returned false with an array.  Thus, it will never
+ *       return false.
+ */
+class HTMLPurifier_ChildDef_Optional extends HTMLPurifier_ChildDef_Required
+{
+    /**
+     * @type bool
+     */
+    public $allow_empty = true;
+
+    /**
+     * @type string
+     */
+    public $type = 'optional';
+
+    /**
+     * @param array $children
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return array
+     */
+    public function validateChildren($children, $config, $context)
+    {
+        $result = parent::validateChildren($children, $config, $context);
+        // we assume that $children is not modified
+        if ($result === false) {
+            if (empty($children)) {
+                return true;
+            } elseif ($this->whitespace) {
+                return $children;
+            } else {
+                return array();
+            }
+        }
+        return $result;
+    }
+}
+
+// vim: et sw=4 sts=4