Declare timestamp parameter of http_conditionalRequest as int

inc/httputils.php

@@ -15,7 +15,7 @@ define('HTTP_CHUNK_SIZE',16*1024);
  *
  * @author   Simon Willison <swillison@gmail.com>
  * @link     http://simonwillison.net/2003/Apr/23/conditionalGet/
- * @param    timestamp $timestamp lastmodified time of the cache file
+ * @param    int $timestamp lastmodified time of the cache file
  * @returns  void or exits with previously header() commands executed
  */
 function http_conditionalRequest($timestamp){