I think "Number" is a better name than "Float". It's a much more common word which I immediately get a feeling for. That typeof NaN === 'number' really makes sense for me, and I feel that most wouldn't need a long explanation to get it either.
Though if they're not calling them floats, maybe they could have also come up with a better name for NaN. If they used, say, "ERR", it would be something many people had seen before (from calculators) and we'd get to stop hearing people bitch about "NotANumber is a number WTF".
(I suppose "they" in this case must be the hypothetical well-treated team that didn't develop JavaScript instead of a frustrated Brendan Eich.)