Remove check for `done` variable at test end
Remove check for `done` variable at test end

The `done` variable is not used anywhere and async tests are not
supported yet, so remove this unnecessary check.

mpeterv/busted,nehz/busted,ryanplusplus/busted,o-lim/busted,DorianGray/busted,istr/busted,sobrinho/busted,xyliuke/busted,Olivine-Labs/busted