Oh no it isn't! There's no such thing!
If you've got a '1989' Dome yourself, that should be much the same as this one, shouldn't it, with cantis etc? The 1989/90 Domes as per the '1990' catalogue were made in several colours, including this white, although ironically I've never seen one in the colour shown in the catalogue.
Kona didn't really worry about model years then, but I would guess that your bike, like this one, is what is generally known as a '1990'. i.e., it might well have a T89 serial number and might well have been first purchased in 1989, but it's the bike in the '1990' catalogue, aside from the colour?
The previous (first) range that are often known as 1988, but would be known as 1989 on the later basis, just had three bikes - Fire Mountain, Cinder Cone and Explosif. All are identifiable by their rear U-brakes.
I'm just down the road from this seller, so I might ask to go and see it. Just out of interest though, as it's four sizes too big for me!