It happens because we have type casting operators for both types RefPtr<*Type*> and PassRefPtr<*Type*>. I think we can drop PassRefPtr type casting operator and use a named function 'release'.
Created attachment 139964 [details] Patch
Comment on attachment 139964 [details] Patch Clearing flags on attachment: 139964 Committed r115965: <http://trac.webkit.org/changeset/115965>
All reviewed patches have been landed. Closing bug.