Function checkDangerIterClosing

lib/web/polyfill.js:555–566

(fn)

  return entries ? invoke(fn, value) : fn(value);
}
function checkDangerIterClosing(fn){
  var danger = true;
  var O = {
    next: function(){ throw 1 },
    'return': function(){ danger = false }
  };
  O[SYMBOL_ITERATOR] = returnThis;
  try {
    fn(O);
  } catch(e){}
  return danger;
}
function closeIterator(iterator){
  var ret = iterator['return'];
  if(ret !== undefined)ret.call(iterator);