change the source map bias to LEAST_UPPER_BOUND, fix reporting of destructuring assignment
change the source map bias to LEAST_UPPER_BOUND, fix reporting of destructuring assignment

rtsao/babel-istanbul,RubaXa/babel-istanbul,RubaXa/babel-istanbul,slonoed/babel-istanbul,RubaXa/babel-istanbul,GalenWarren/babel-istanbul,ambitioninc/babel-istanbul,ambitioninc/babel-istanbul,GalenWarren/babel-istanbul,ambitioninc/babel-istanbul,rtsao/babel-istanbul,rtsao/babel-istanbul,slonoed/babel-istanbul,GalenWarren/babel-istanbul,slonoed/babel-istanbul