ToPrimitive 
by 前端子鱼 @mwc
Convert a property of type literal (label type) to a primitive type.
For example
```typescript
type X = {
name: 'Tom',
age: 30,
married: false,
addr: {
home: '123456',
phone: '13111111111'
}
}
type Expected = {
name: string,
age: number,
married: boolean,
addr: {
home: string,
phone: string
}
}
type Todo = ToPrimitive // should be same as `Expected`
```
