Blame Donald Trump’s ruthless bigotry, sure. But when the president walked into the Oval Office, he walked into a ready-made, bipartisan immigration policy framework poised for brutality. Militarized borders, deportation squads, an archipelago of internment facilities, hypertrophied executive power, a lurid body of national security and anti-trafficking law sprung from the rich manure of panic — none of this is Mr. Trump’s handiwork. It was an inheritance.