Hello,
A browser is just an program with a specified function: in this case, accessing the internet. This game is one of the things it accesses. The miniclient is a more specified program. It accesses only the game. As such, it is easier to make, run, develop, and upkeep.
Additionally, What you are asking for....Is a miniclient. But with browser capabilities. I would suggest that you use the miniclient and simultaneously use a web browser.
Thanks!