[Bug Report] popup-picker 组件异步请求数据，不渲染

### VUX version
2.9.2

### OS/Browsers version
Windows Google浏览器

### Vue version
2.5.2

### Code

```html
文件index.vue

export default {
data(){
return{
cityTitle: '18-07-08',
cityValue:[],
citysList: [],
}
},
methods:{
/**
* parentId: 父级id，默认为0
* type: 子节点类型 省：province 市：city 区：district
*/
getChildCitys(id,type){
this.$api.get(this.$interface.apiurl.getChildCitys,{
parentId: id,
type: type
},res=>{
console.log(res);
if(type === 'province'){
this.nowProvince = res.data;
this.citysList[0] = [];
this.getChildCitys(res.data[0].id,"city");
this.$nextTick(()=>{
for (let i = 0; i < res.data.length; i ) {
this.citysList[0].push(res.data[i].name);
}
})
}else if(type === 'city'){
this.citysList[1] = [];
this.$nextTick(()=>{
for (let i = 0; i < res.data.length; i ) {
this.citysList[1].push(res.data[i].name);
}
})
}
})
}

},
activated() {
this.getChildCitys(0,'province');
},
}

```

### Steps to reproduce
进入页面，点击popup-picker

### What is Expected?
数据正常渲染

### What is actually happening?
数据不正常渲染