真机调试时，iphone6 ios12上部分机子无法加载aes.js

• 当前 Bug 的表现（可附上截图）

• 预期表现

• 复现路径

• 提供一个最简复现 Demo

选择真机调试时，用户iphone6手机无法加载aes.js，这个是网上通用的小程序aes加密解密，只有部分机子会这样。

[publib]:834 TypeError: Cannot assign to read only property ‘toString’ of object ‘#<Object>’

    at s.mixIn (aes.js:31)

    at Object.extend (aes.js:16)

    at aes.js:38

    at aes.js:8

    at require ([publib]:1)

    at [publib]:1

    at bledataparse.js:1

    at require ([publib]:1)

    at [publib]:1

    at deviceinfo.js:4

loadCode @ [publib]:834

handleInitUserCode @ [publib]:812

handleSetupContext @ [publib]:1225

handleProcessMessage @ [publib]:1234

ws.on @ [publib]:1462

emitOne @ events.js:115

emit @ events.js:210

_receiver.onmessage @ C:\Users\xxx\AppData\Roaming\Tencent\微信web开发者工具\package.nw\node_modules\ws\lib\WebSocket.js:146