I accidentally navigated to one of those sites that pops up a dialog telling me that my computer is infected. Upon clicking the OK button, that dialog reappears, ad infinitum.
I cannot close the tab or otherwise interact with Safari while the dialog is up. No matter how many times I Quit or Force Quit (and no matter how many times I tell Safari "Do Not Re-open Windows") the previously-open set of tabs always reopens and this dialog pops to the fore.
How can I delete the state of things while Safari is closed?