Donald Trump unbosomed himself of yet another pair of catty and adolescent tweets this morning, resulting in the usual fuss. Yes, Mr. Trump has been the object of relentless personal assault, and the vilest invective, since he became a candidate, but we expect that sort of thing from the spoiled and sullen Left. Would it be too much to ask that the President refrain from such low — and above all, wholly counterproductive — gossip and sniping?