[Bug Report] XAddress 添加title slot 报错

### VUX version
2.7.7

### OS/Browsers version
Chrome 65.0.3325.181

### Vue version
2.5.3

### Code

```html


qwe


```

### Steps to reproduce
为XAddress 添加title slot 报错：
Duplicate presence of slot "title" found in the same render tree - this will likely cause render errors.

### What is Expected?
自定义title的样式

### What is actually happening?
为XAddress 添加title slot 报错：
Duplicate presence of slot "title" found in the same render tree - this will likely cause render errors.