Docs: Add a reminder to the DocBlock description for `add_query_arg()` mentioning that the output is not escaped by default.

Props brentvr for the initial patch. (first props!)
See #33912. See #32246.

Built from https://develop.svn.wordpress.org/trunk@34264


git-svn-id: http://core.svn.wordpress.org/trunk@34228 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -680,6 +680,10 @@ function _http_build_query( $data, $prefix = null, $sep = null, $key = '', $urle
  * value. Additional values provided are expected to be encoded appropriately
  * with urlencode() or rawurlencode().
  *
+ * Important: The return value of add_query_arg() is not escaped by default.
+ * Output should be late-escaped with esc_url() or similar to help prevent
+ * vulnerability to cross-site scripting (XSS) attacks.
+ *
  * @since 1.5.0
  *
  * @param string|array $param1 Either newkey or an associative_array.

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-34263';
+$wp_version = '4.4-alpha-34264';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.