No, not really. But then I don't care for browser based games. Not even on the computer.
Not that this addresses what you are really talking about (or what I think you are really talking about), but if you do a search for HTML5 mobile games for iPad, you'll turn up a few sites that do host games you can play.
So, at least technically, it is possible to play a few games in Safari.
They tend to be poor games, optimized for phones, and often (inexplicably) despite this not working with a touch UI, but they exist as a kind of reminder that it is possible. It's just that developers have found the App Store a far better place to make money; and even when it's not about money, the quality of local apps (especially games) triumph web based games in every way.
While on safari, you would be wise to avoid playing games and instead watch out for savage and ill-disposed creatures such as elephants, that might otherwise sneak up unnoticed and trample on you.