Ensure a user exists in get_comment_author().

props azaozz.
see #24084.

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git-svn-id: http://core.svn.wordpress.org/trunk@25116 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Initialize kses filters if _wp_unfiltered_html_comment nonce isn't set.

See #24752.

Built from https://develop.svn.wordpress.org/trunk@25137


git-svn-id: http://core.svn.wordpress.org/trunk@25117 1a063a9b-81f0-0310-95a4-ce76da25c4cd