A hateful antisemite spat on an 8-year-old Jewish boy outside a Brooklyn synagogue, cruelly telling the youngster and his friends that “Hitler should have killed you all,” cops said Wednesday. The woman, dressed in an orange hoodie, black leggings and black Uggs, can be seen on surveillance video storming up to the boy and two other children on Avenue P near Coleman St. in Marine Park just after 12:30 p.m. Friday. The children were standing in front of the Kehal Tiferet Avrohom Ziditshov Orthodox synagogue, according to cops. The woman stood in front of them and shouted, “Hitler should have...