Add support for pug nested syntax

```javascript
function Counter(props) {
  const [count, setCount] = useState(0)
  useEffect(() => {
    document.title = `You clicked ${count} times`
  })
  return pug`
    div.red.f1
      if props.showGreeting
        p.greeting Hello #{props.name}!
      button(
        onClick=()=>setCount(count + 1)
      ) #{count} Click Me
`}
```