73927 - use batch deleting for history (a speedup of 30000% for a few hundred items!).
63292 - session additions to global history are lost on a crash.
112308 - 2M history.dat file adds 30% to startup time.
96753 - changing history grouping doesn't update open sidebar panels.
98776 - support context menus on folders in global history.
124665 - can't clear global history after startup if you don't have a homepage.
93233 - with large history, clear history appears to hang.
92613 - shouldn't store chrome uris in global history.
59816 - clear history button should be disabled if history is empty; add count attr to nsIBrowserHistory.
104231 - last typed web location remains after clearing all history.
r=ben sr=alecf
git-svn-id: svn://10.0.0.236/trunk@114302 18797224-902f-48f8-a5cc-f745e15eee43
99107e3775