Index: src/wp-includes/kses.php
===================================================================
--- src/wp-includes/kses.php	(revision 34670)
+++ src/wp-includes/kses.php	(working copy)
@@ -97,6 +97,9 @@
 			'src' => true,
 		),
 		'b' => array(),
+		'bdo' => array(
+			'dir' => true,
+		),
 		'big' => array(),
 		'blockquote' => array(
 			'cite' => true,