in WP 4.7 plugin don’t remove dns-prefetch…

This code not work:

/**
 * Remove emoji CDN hostname from DNS prefetching hints.
 *
 * @param  array  $urls          URLs to print for resource hints.
 * @param  string $relation_type The relation type the URLs are printed for.
 * @return array                 Difference betwen the two arrays.
 */
function disable_emojis_remove_dns_prefetch( $urls, $relation_type ) {
	if ( 'dns-prefetch' == $relation_type ) {
		/** This filter is documented in wp-includes/formatting.php */
		$emoji_svg_url = apply_filters( 'emoji_svg_url', 'https://s.w.org/images/core/emoji/2/svg/' );

		$urls = array_diff( $urls, array( $emoji_svg_url ) );
	}

	return $urls;
}

this code helped me

add_filter('emoji_svg_url', '__return_empty_string');