The mayfly ability from /ability does not affect spectator mode players

I don't know if this is intentional or not, but players in spectator mode do not have their ability to fly revoked whenever /ability is used. If this were to be intentional, there still is a message which states that the ability to fly is revoked whilst the player can still fly. There either needs to be a error stating you cannot turn of flight for spectators or the command should stop then from flying.