Used to be present (see revisions) but the browser itself was discontinued.
Used to be present (see revisions) but AppleScript support was removed. Even when it had AppleScript support, it was undocumented.
Absent since although it’s possible to get the window’s title, it’s not possible to get its URL (it used to be, in versions prior to and including
3.5). It’s possible via hacky ways that consist of sending keystrokes, but those can be unreliable. This bug is being tracked in Bugzilla.