WARSAW, Poland — Two Polish historians are facing a libel trial for a scholarly examination of Polish behavior during World War II, a case whose outcome is expected to determine the fate of independent Holocaust research under Poland’s nationalist government.A verdict is expected in Warsaw’s district court on Feb. 9 in the case against Barbara Engelking, a historian with the Polish Center for Holocaust Research in Warsaw, and Jan Grabowski, a professor of history at the University of Ottawa.It is the …