By Dave Graham MEXICO CITY (Reuters) -Nine out of ten Mexicans voting on Sunday in an unprecedented recall election engineered by President Andres Manuel Lopez Obrador backed him to stay in office, underlining his domination of a polarized political agenda. Both critics and supporters alike had viewed his victory as a foregone conclusion in a ballot that had fed speculation it could open the door to extending presidential term limits, now limited to a single six-year period. Between 90.3% and 91.9% voters were predicted to have supported Lopez Obrador, a preliminary estimate from the National …