Added SuppressEventHandlers() utility routine, which PreDestroy() and CreateAnonymousContent() now call to determine if the controller unregister/register code should be executed. r=rods@netscape.com sr=sfraser@netscape.com adt=jaimejr@netscape.com a=asa@mozilla.org git-svn-id: svn://10.0.0.236/trunk@118752 18797224-902f-48f8-a5cc-f745e15eee43