Issue: https://github.com/php/php-src/issues/8137
Author: kenylieou
### Description
The following code:
```php
ini_set('display_errors', 1);
$d = new DOMDocument();
$html =
"<html><body><span>test1</span><span>\x0</span><span>test2</span></body></html>";
$d->loadHTML($html);
$newHtml = $d->saveHTML();
echo htmlentities($newHtml);
<?php
```
Resulted in this output:
```html
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html><body><span>test1</span><span></span></body></html>
```
But I expected this output instead:
```html
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html><body><span>test1</span><span></span><span>test2</span></body></html>
```
### PHP Version
PHP 7.4.28, PHP 8.1.0
### Operating System
WSL Docker Ubuntu