To the chagrin of many Brooklyn Heights residents, any chance that the former 84th Street Precinct building at 72 Poplar Street would be converted to housing is now gone. According a tipster, a lease went out last week to the League Treatment Center, a program for developmentally and emotionally challenged that is losing its lease at 30 Washington in Dumbo in a couple of years. This possibility was originally floated in the Brooklyn Eagle back in November; as recently as December 19, however, area residents were lobbying CB2 to support a residential variance for the 30,000-square-foot building in the hopes of avoiding this very outcome. GMAP