allow to edit comment on the articles which are not theirs

gistfile1.php

function rb_add_role( $allcaps, $caps, $args ){
    global $post;
    if( 'edit_comment' == $args[0] ) {
        foreach ($caps as $cap) {
            if( ! array_key_exists($cap, $allcaps) ) {
                $allcaps[$cap] = 1;
            }
        }
    }
    return $allcaps;
}
add_filter( 'user_has_cap', 'rb_add_role', 10, 3 );