Joke if you will. The Stones are used to it, going all the way back to wisecracks about their “Steel Wheelchairs” tour back in the ‘80s. But they just keep rocking — and they certainly don’t act their age, at least onstage. Far from it. In fact, they were back in all their energetic, timeless glory in Cleveland on Saturday for a show at Cleveland Browns Stadium, their first time here since 2002.