A robotic plane deliberately dropped a bomb near a truck at Edwards Air Force Base on Sunday, marking another step forward for technology the U.S. military hopes will one day replace human pilots on dangerous combat missions. Under human supervision but without human piloting, a prototype of Boeing's X-45 took off from the desert base, opened its bomb bay doors, dropped a 250-pound Small Smart Bomb and then landed. The inert bomb struck within inches of the truck it was supposed to hit, Boeing said, adding that had the bomb contained explosives, the target would have been destroyed. "It's absolutely...