Fetch support for explicit resource management

[jasnell]

What is the issue with the Fetch Standard?

This goes along with the streams-specific related discussion here: whatwg/streams#1307

What, if any, support should the fetch spec adopt for explicit resource management (https://github.com/tc39/proposal-explicit-resource-management). I'm specifically thinking of the Request and Response objects here. Let's focus tho more generally on anything that includes the Body mixin...

Should Body be disposable and what would that mean?

using response = await fetch('http://example.org');

Specifically, if the body payload has not been fully read, would dispose cancel the remaining read and cause outstanding promises to be rejected? Or should Request/Response/Body just not be disposable?