微信PC客户端不支持object.assign方法
Recently, I encountered a bug: my frontend project can work normally in WeChat mobile clients but when visited in WeChat PC client for window OS, the page turned out be be blank -_-. After some attempts, I found that it's due to the unavailability of Object.assign method in WeChat PC client for window OS. Therefore, we need to write polyfill for Object.assign method. There is not need to think how to write this polyfill ourselves. Just copy from MDN ^_^.
