Nearly two decades after the Exxon Valdez ran around on Bligh Reef in Prince William Sound, the U.S. Supreme Court has taught Exxon (now ExxonMobil) and corporations everywhere a lesson: Don't pay off legal judgments. Stall, stall, stall for 19 years. Courts have held that Exxon must pay $2.5 billion in punitive damages for spilling…