Issues with changing innerHTML

```html

Press me

document.querySelector('#btn').addEventListener('click', () => {
document.body.innerHTML += '<p>Hello</p>';
});

```

Two things happen when the button is pressed:

1. The button gets removed.
2. `` gets added as the first element of the body.

Reproduce the provided amp-script example and trace the document.body.innerHTML setter and DOM update path in worker-dom. Check why appending a paragraph removes the button and inserts an empty q element; done means the button remains and only the requested paragraph is added.

Written by the indexing model from the issue text.