get `moz-extension` scheme file throws `ClientException: Invalid content-length header [-1]`

Getting a file from a firefox extension, returns `Content-length` is `-1`.

Because of this, `get` method throws a `ClientException: Invalid content-length header [-1].` exception.

```dart
await get('moz-extension://<extension-id>/index.html')
```

Should that check be disabled for `moz-extension` scheme ?


> http version : 1.2.1