Introduce get the MIME type for Request/Response (thanks CYBAI!)
The Fetch standard defines requests, responses, and the process that binds them; fetching.
Joined November 2014
- Be more selective with handing out the internal response
- Use response's internal response at end of fetch handover (thanks noamr!)
- Account for removal of AbortSignal's follow
- Fully read's processBodyError argument needs to take an exception

