strict, moderate, and default, where
default corresponds to Mozilla's behavior prior to
our changes.
When a user enables JavaScript in Advanced Preferences,
she can now select one of these three security policies
as her global security policy.
Moreover, there is a table of site security policies,
initially empty, where she can add, delete, or edit
site security policy selections.
This facility allows her to enter a hostname or URL in
a text field and to mark a checkbox for the desired
policy (strict, moderate, default).