Prevent a JS error when working with embedded media in TinyMCE.

props wonderboymusic. fixes #23876.



git-svn-id: http://core.svn.wordpress.org/trunk@23895 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Prevent classid="clsid:undefined". props SergeyBiryukov. see #23876.



git-svn-id: http://core.svn.wordpress.org/trunk@23896 1a063a9b-81f0-0310-95a4-ce76da25c4cd