WordPress 3.9 gallery

<?php
function prefix_gallery_atts( $atts ) {
 $atts['itemtag'] = 'figure';
 $atts['icontag'] = 'div';
 $atts['captiontag']= 'figcaption';
 
 return $atts;
}
add_filter( 'shortcode_atts_gallery', 'prefix_gallery_atts' );
?>

• http://themeshaper.com/2014/03/04/html5-galleries-in-wordpress-3-9/(@source)