#61140 - delete history.dat if it gets corrupted #56867 - implement "First Visited" #19370 - implement "Visit Count" #33697 - clean up nsGlobalHistory::OpenDB a bit more (doesn't fix the leak yet) sr=waterson git-svn-id: svn://10.0.0.236/trunk@83493 18797224-902f-48f8-a5cc-f745e15eee43