Function wrapper

test/babel.js:48596–48600

(get)

	    InternalMap;

	var wrapper = function wrapper(get) {
	  return function WeakMap() {
	    return get(this, arguments.length > 0 ? arguments[0] : undefined);
	  };
	};

	var methods = {
	  // 23.3.3.3 WeakMap.prototype.get(key)