Saturday’s GOP debate finally clarified the Donald Trump phenomenon. After months of dominating the polls and millions of words of analysis, the grueling slog of the primary race is finally bringing the facts into sharp relief. Donald Trump isn’t a revolutionary. He’s not a conservative. He’s not even a populist. He’s a Democrat. In the Greenville, S.C., debate, Jeb Bush and Ted Cruz both got under Trump’s skin, and he cracked. He shouted his true feelings, and they were ugly to see. Regarding the Iraq War, Trump made it quite plain that he believes the fever-swamp “Bush lied, people diedâ€...