LOS ANGELES (Reuters) - R&B singer Chris Brown had his probation revoked on Monday by a judge in Los Angeles after he was charged in a hit-and-run traffic accident last month. Brown, who has been on probation for criminal assault for beating his former girlfriend and fellow R&B singer, Rihanna, on the eve of the 2009 Grammy Awards in Los Angeles, could face jail time if he is found to have violated his probation. ...