HEAD requests fail (Tabris.js 2.9.0)

### Problem description

Sending a `HEAD` request raises an exception:

```
TypeError: Receiver is detached
slice@[native code]
_initBody@http://...:8081/node_modules/tabris/tabris.min.js:1:156754
Response@http://...:8081/node_modules/tabris/tabris.min.js:1:159191
@http://...:8081/node_modules/tabris/tabris.min.js:1:160299
trigger@http://...:8081/node_modules/tabris/tabris.min.js:1:17197
$trigger@http://...:8081/node_modules/tabris/tabris.min.js:1:27466
_notify@http://...:8081/node_modules/tabris/tabris.min.js:1:43843
_notify@[native code]
```
This works as expected with latest Tabris.js 3.

### Environment

- Tabris.js version: 2.9.0
- Device: iPad
- OS: iPadOS 16.6

### Code snippet

```js
fetch('https://google.de', {method: 'HEAD'})
.then(r => console.log(r.status))
.catch(e => console.log(e));
```