[Bug Report] switch的change事件返回值有问题

### Mint UI version
2.2.13

### OS/Browsers version
windows 10

### Vue version
2.6.10

### Reproduction Link
https://jsfiddle.net/37uyg9jh/2/

### Steps to reproduce

methods: {
changeHappened(e){
console.log(e,this.checked)
},
}

### What is Expected?
console出来的结果一直

### What is actually happening?
在mt-switch中不一样 但el-switch是正确的 我想提mt-switch 的bug但是自动跳转的页面引入的是el

Start with the linked JSFiddle reproduction and compare the value received by mt-switch's change handler with the corresponding el-switch behavior. The issue does not name a source file or test, and the expected callback value is unclear; clarify that expectation before locating the switch implementation and adding coverage.

Written by the indexing model from the issue text.