[LAWS]Dead: The ball is out of play. This happens when the ball has gone outside the playing area and remained there, or when the referee has blown the whistle to indicate a stoppage in play, or when a conversion kick has been taken.[/LAWS]
The way I understand/interpret that law definition is that the game doesn't restart between try and conversion.
As such, the law clearly states that the ball isn't dead after a try, The ball only becomes dead when the full try+conversion has been completed. And hence, the match doesn't restart until the... well... restart.
It is consistent with the rest of the law to see try+conversion as a single stoppage. That's why the conversion is taken even if a try is scored after the time is up...
Doesn't that make sense?
My 2 cents,
Pierre.