The new get_post_types_by_support() function in WordPress 4.5 is located in wp-includes/post.php on lines 1641-1661

post.php

<?php

/**
 * Retrieves a list of post type names that support a specific feature.
 *
 * @since 4.5.0
 *
 * @global array $_wp_post_type_features Post type features
 *
 * @param array|string $feature  Single feature or an array of features the post types should support.
 * @param string       $operator Optional. The logical operation to perform. 'or' means
 *                               only one element from the array needs to match; 'and'
 *                               means all elements must match; 'not' means no elements may
 *                               match. Default 'and'.
 * @return array A list of post type names.
 */
function get_post_types_by_support( $feature, $operator = 'and' ) {
	global $_wp_post_type_features;

	$features = array_fill_keys( (array) $feature, true );

	return array_keys( wp_filter_object_list( $_wp_post_type_features, $features, $operator ) );
}