Condition multiply inherits so the Builder::disposeBuilder call was missed

and prenotify occurs during ::dispose when there is no m_pConditionPlayground
anymore, so m_pConditionPlayground == 0 where pPlaygroundCandidate is 0
passes, so a random widget gets cast to somethings its not, hence the bad
cast exception

Change-Id: I6d081dd55df1a68ab893294858e1ab0054d5e049