[Bug Report] $listeners is readonly and $attrs is readonly

### Mint UI version
2.2.10

### OS/Browsers version
mac/chrome62

### Vue version
2.5.3

### Reproduction Link
[https://jsfiddle.net/pj71jkyw/](https://jsfiddle.net/pj71jkyw/)

### Steps to reproduce
当我在vue2.0项目中使用Mint-ui组件时候，我试图去改变一个变量的值,这个变量就是一个普通变量，不是Mint-ui组件的props，此时会报
vue.runtime.common.js?da27:569 [Vue warn]: $attrs is readonly.
found in

--->
at /Users/tsz/Desktop/speech_project/web-robot/src/pages/config/child/set_photo.vue
at /Users/tsz/Desktop/speech_project/web-robot/src/pages/config/index.vue

vue.runtime.common.js?da27:569 [Vue warn]: $listeners is readonly.

found in

--->
at /Users/tsz/Desktop/speech_project/web-robot/src/pages/config/child/set_photo.vue
at /Users/tsz/Desktop/speech_project/web-robot/src/pages/config/index.vue

### What is Expected?
不报警告

### What is actually happening?
报警告