WML*Element classes mostly implement insertedIntoDocument(), not removedFromDocument().
The only case where this is relevant in WML is error handling. The parsed WML tree fragment is inserted in an XHTML compound error document. This requires removedFromDocument() to be correctly implemented otherwhise we run into trouble (visible when using run-webkit-tests fast/wml --random).
Created attachment 33681 [details]
Comment on attachment 33681 [details]
After Niko walked me through it over chat I can't find anything wrong. Drats :)
Landed in r46510.