Remove incorrect set of bodyUsed flag when cloning a request

[morsdyce]

This removes setting bodyUsed to true when you clone a request.

In order to use a request multiple times you need to clone a request, which lets you get a copy of the request while leaving the original request as is, as long as you didn't read the request body beforehand.

In Chrome implementation for example cloning a request does not change the bodyUsed property to true, however in this polyfill it does.

This prevents you from cloning a request and passing on the original request as passing it causes the Already Read exception even though the body was not read directly from that request (by the end user).

Polyfill scenario:
https://runkit.com/58308876f439290014bb0025/5830907cf836f700146fa4f7

Chrome Implementation scenario: (open the browser console to see the output)
https://plnkr.co/edit/OVK9RREqhMm3WcgPtxOf?p=preview

Sorry for not having a single place for both scenarios. I could not find a snippet service that allows me to bring the package from npm.

TL;DR
bodyUsed should not be set to true when cloning a request on the original request

[mislav]

Thanks, but if you tried to add a failing test before coding up a solution, you would have found out that bodyUsed is not actually set to true. We have tests to verify that behavior as well. We only had tests to verify requests with bodies, though, so I've added a new test that verifies this behavior for GET request too, like in your runkit example.