Voters in El Salvador this week gave their tough-on-crime president a sweeping mandate: Keep going. While votes are still being counted‚ President Nayib Bukele claims he won re-election by a landslide‚ with more than 85 percent of the vote. If those results hold when the official count is announced‚ not even Latin America’s best-known populist presidents‚ like Venezuela’s Hugo Chávez or Bolivia’s Evo Morales‚ will have come close to winning election by such margins. Mr...