Ok, I have added them.

What would you think of a patch like this for core?
https://github.com/WordPress/WordPress/blob/master/wp-includes/comment-template.php#L1826-L1841

```
	$defaults = array(
		'walker'            => null,
		'max_depth'         => '',
		'style'             => current_theme_supports( 'html5', 'comment-list' ) ? 'ol' : 'ul',
		'callback'          => null,
		'end-callback'      => null,
		'type'              => 'all',
		'page'              => '',
		'per_page'          => '',
		'avatar_size'       => 32,
		'reverse_top_level' => null,
		'reverse_children'  => '',
		'format'            => current_theme_supports( 'html5', 'comment-list' ) ? 'html5' : 'xhtml',
		'short_ping'        => current_theme_supports( 'html5', 'comment-list' ) ? true : false,
		'echo'              => true,
	);
```