api: in getStats(), directly rewrote activePads as an expression
api: in getStats(), directly rewrote activePads as an expression

Instead of creating an empty Set and then mutate it.

ether/etherpad-lite,joequant/etherpad-lite,joequant/etherpad-lite,ether/etherpad-lite,joequant/etherpad-lite,ether/etherpad-lite,storytouch/etherpad-lite,joequant/etherpad-lite,storytouch/etherpad-lite,storytouch/etherpad-lite