MEXICO CITY (Reuters) - Mexican gross domestic product (GDP) likely contracted slightly in the fourth quarter, rounding off a weak year in which the economy has been teetering on the brink of recession, a Reuters poll showed on Monday.The median forecast of a poll of 12 analysts is that GDP shrank 0.1% in seasonally-adjusted terms during the October-December period compared with the previous quarter.That follows stagnation in the July-September period and a contraction of 0.1% in the second..