遍历关键字 in 错误按照of解析

[code-sunbo]

测试代码：
let list = [4, 5, 6];

for (let i in list) {
console.log(i); // "0", "1", "2",
}

for (let i of list) {
console.log(i); // "4", "5", "6"
}

实际in 三地址码结果与of相同