sr=jst, r=roc+mozilla@cs.cmu.edu, a=asa make sure we always post new invalidate events to the topmost queue, and don't skip creating new reflow events just because we happen to have one an elder queue. git-svn-id: svn://10.0.0.236/trunk@125843 18797224-902f-48f8-a5cc-f745e15eee43