WASHINGTON (Reuters) - The U.S. trade deficit shrank in December to its narrowest in nearly three years, suggesting the economy did much better in the fourth quarter than initially estimated. The country's trade gap narrowed to $38.5 billion during the month, the Commerce Department said on Friday. Analysts polled by Reuters had expected a deficit of $46 billion. That suggests the U.S. government will revise upward its advance reading for fourth-quarter gross domestic product, which showed the economy contracted at a 0. ...