In wp_new_comment check for presence of $_SERVER['REMOTE_ADDR']

[rachelbaker]

To create comments with the WP REST API, we would like to use wp_new_comment(). This would allow us to take advantage of the filters, actions, and notifications already baked into wp_new_comment().

'wp_new_comment()' does not allow the passing of 'comment_author_IP' and only sets the value from $_SERVER["REMOTE_ADDR"].

For API use the REMOTE_ADDR attribute would not be reliable or populated, and will trigger a PHP Notice of Undefined Index.

https://core.trac.wordpress.org/browser/tags/4.1/src/wp-includes/comment.php#L2073

[SergeyBiryukov]

Duplicate of #14601.