@-silence an Imagick call that causes a warning in PHP 5.4.

props DH-Shredder. fixes #24539.

git-svn-id: https://core.svn.wordpress.org/trunk@24568 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Remove img_html_to_post_id(). It's unused since [24555]. fixes #24610.

git-svn-id: https://core.svn.wordpress.org/trunk@24569 1a063a9b-81f0-0310-95a4-ce76da25c4cd