For President Donald Trump, it may prove to be the bounce that never comes. On the afternoon of March 24, the news broke that special counsel Robert Mueller had found no collusion between Trump's campaign and the Russians — a moment for which the president and his allies had been waiting almost two years. But a week later, Trump's average approval rating, according to the Real Clear Politics tracker, had climbed a grand total of one-tenth of one percentage point — to 43.2 percent from 43.1 percent. You could argue, of course, that Americans are reserving judgment. The complete Mueller...