Function wrap

demo/js/index.js:3406–3417

(tag)

} : setDesc;

var wrap = function(tag){
  var sym = AllSymbols[tag] = _create($Symbol.prototype);
  sym._k = tag;
  SUPPORT_DESC && setter && setSymbolDesc(ObjectProto, tag, {
    configurable: true,
    set: function(value){
      if(has(this, HIDDEN) && has(this[HIDDEN], tag))this[HIDDEN][tag] = false;
      setSymbolDesc(this, tag, createDesc(1, value));
    }
  });
  return sym;
};

var isSymbol = function(it){
  return typeof it == 'symbol';