When JPMorgan Chase bought battered Washington Mutual, the third-largest bank in the state, it scored a territorial expansion coup that will spare most branches here. Chase has only two branches in the region, so it probably won’t lay off WaMu workers or close offices in Palm Beach and Broward counties, Ken Thomas, a Miami-based economist and banking analyst, said Friday. WaMu has 36 branches in Palm Beach County and 34 in Broward. It employs 1,100 people in the two counties, but has been cutting operations here in recent years. A mainstay of its Florida business, the so-called multi-option adjustable rate mortgage, was one of the reasons the bank failed in the largest bank collapse in U.S. history.