NAWA, Syria — As insurgents raced across Syria in a surprise offensive launched in the country's northwest late last year, officials from several countries backing either the rebels or Syria’s government met in Qatar on what to do. According to people briefed on the Dec. 7 meeting, officials from Turkey, Russia, Iran and a handful of Arab countries agreed that the insurgents would stop their advance in Homs, the last major city north of Damascus, and that internationally mediated talks would