emit parenthesis when necessary for ops converted to assignments
emit parenthesis when necessary for ops converted to assignments

dj31416/JSX,jsx/JSX,jsx/JSX,mattn/JSX,jsx/JSX,dj31416/JSX,dj31416/JSX,dj31416/JSX,jsx/JSX,mattn/JSX,jsx/JSX,dj31416/JSX