[fetch] Set content-length header of FormData requests? (#239)

I went through the standard and could not figure out if there was a way to set the content-length of a fetch post with FormData as the body. Is that intentional? If not, it would be useful for fetch to automatically set the content-length header as it does for content-type.

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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/fetch/issues/239