This is SO WEIRD.. Yes I absolutely had this dream as a child, floating down the stairs... as previous posters have said, never up - just down! And it's so odd that so many on here had the same dream. 
In fact, I have floated a lot in dreams for many years - not just as a child, but well into adulthood. Even now (at 50-ish) I have the floating dream occasionally, and dream I'm jumping down the road, and I jump up some 6-9 feet, and each 'jump' is around 20-30 feet in length. So I'm doing huge, slow, (but high and long) leaps. Like huge moon walk type steps - if you see what I mean...
I am sometimes flying, (higher than the 6-9 feet, but not usually very far over the houses, around 80-150 feet I would say.) And on other occasions, I am much higher, like 500-1000 feet up. But in all of these dreams I am usually in a familiar place. Not far from home, or somewhere I have visited before and am familiar with.
So unbelievably realistic, and I am always so disappointed when I wake up and realise it's a dream, and in actual fact, I can't fly (or float!)
I am so freaked out that so many people on here have had the same dream (or very similar.)
@EbbyEbs Thanks for posting this! I hope I dream about floating or flying tonight! 