Mozilla's original implementation of this failed a couple of tests, but this seems to solve all the problems. Basically, the caret-color wasn't able to be set differently based on whether a link was visited, and the auto value implementation was incomplete. The only test we fail now is the one where you have grey text on a grey background and the caret is supposed to be visible, but I think that may have been removed from the spec. Even if it wasn't, no other browser supports it anyway.
