[fetch] specify types of streams (#167)

I have been wondering what the type of the stream returned by 

I am using the Fetch API's [fetch method](https://fetch.spec.whatwg.org/#fetch-method) which [returns a Promise of a Response](https://fetch.spec.whatwg.org/#response), which contains a `body` which is a `ReadableStream`. From this I can then get chunks for my parser.

Since the streams do not specify the type of a chunk ( see [issue 410 of streams api](https://github.com/whatwg/streams/issues/410) ) it would be helpful if the documentation in the Fetch API made clear what type of stream was returned.

Now it is true that the [Response.body](https://fetch.spec.whatwg.org/#concept-body) method says:

> A `body` is a byte stream. It has an associated transmitted which is an integer and initially 0, length which is an integer and initially 0, and error flag which is initially unset.

So I suppose that means the content of the chunk contains bytes, but it is not clear that this means that all chunks will be  `Uint8Array`s

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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/fetch/issues/167