The History Sidebar panel is now a part of Mozilla, you no longer need to download it from here.
Many people have been waiting for the completely functional bug 32594 to be committed. So you don't have to wait for it, I've wrapped up the attachments and turned them into a package. If you've installed the Links Panel you know the drill. First install the History Panel package then restart your browser and finally type chrome://history/content/addpanel.xul into the URLbar and hit enter.