This flag was introduced in r56757 via bug 36692 as a way of circumventing file access policy for file:// origins. It has some inconsistencies, in that it is used to treat only file:// URLs as unique origins (see toString()), but can be turned on for an origin with any local protocol (see Document::initSecurityContext()). At best, this concept gets refactored out into something else that makes more sense. At worst, this function and member variable gets renamed to something that better explains its purpose.
*** This bug has been marked as a duplicate of bug 182227 ***
I just stumbled on this. I need a getter for this property. I think that means finders-keepers.
Never mind. This FIXME is not about this not following getter/setter naming conventions. It's about something more subtle.