The gunman who shot former President Donald Trump at a Pennsylvania rally on Saturday flew a drone over the rally site a few hours before Trump took the stage. The drone, made by DJI, allowed the 20-year-old gunman, Thomas Crooks, to get an overhead view that may have helped him plan his attack, the source said. Trump was shot in the ear in the assassination attempt, and the Secret Service killed Crooks after the attack at the Trump rally in Butler, Pennsylvania. Read: Secret Service Snipers Knew Would-Be Trump Assassin Was On The Roof 20 Minutes Before First Shot Fired The Wall Street Journal…