Unto the manor born, as they say: Romney’s speech was billed by his advisers as his closing argument before the GOP nomination fight kicks off in earnest with the Iowa caucuses on January 3. But you would be forgiven for thinking it sounded more like the opening salvo in a general election. Romney drew no explicit or, really, implicit contrasts with any of his Republican rivals, training his fire exclusively on the Democrat in the Oval Office. His focus reflected a strategy from which his campaign has rarely deviated all year long. But it was also born of a confidence...