Commented Issue: TransferEncodingChunked=true doesn't work on WebHost [1124]

When setting response.Headers.TransferEncodingChunked, the response doesn't get chunked, and a client (Fiddler) will fail trying to read the response.

Repro 1:
public HttpResponseMessage Get()
{
HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
response.Headers.TransferEncodingChunked = true;
response.RequestMessage = Request;
return response;
}

Repro 2:
public HttpResponseMessage Get()
{
HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
response.Content = new LazyContent();
response.Headers.TransferEncodingChunked = true;
response.RequestMessage = Request;
return response;
}

public class LazyContent : HttpContent
{
protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
{
stream.WriteByte(0);
return Task.FromResult<object>(null);
}

protected override bool TryComputeLength(out long length)
{
length = 0;
return false;
}
}

Comments: Just FYI...WebHostBufferPolicySelector is the one which causes whether the responses are chunked or not. So the above scenario, you would need to override WebHostBufferPolicySelector to add a condition for not buffering LazyContent. Following the code: ``` /// <summary> /// Determines whether the host should buffer the <see cref="HttpResponseMessage"/> entity body. /// </summary> /// <param name="response">The <see cref="HttpResponseMessage"/>response for which to determine /// whether host output buffering should be used for the response entity body.</param> /// <returns><c>true</c> if buffering should be used; otherwise a streamed response should be used.</returns> public virtual bool UseBufferedOutputStream(HttpResponseMessage response) { if (response == null) { throw Error.ArgumentNull("response"); } // Any HttpContent that knows its length is presumably already buffered internally. HttpContent content = response.Content; if (content != null) { long? contentLength = content.Headers.ContentLength; if (contentLength.HasValue && contentLength.Value >= 0) { return false; } // Content length is null or -1 (meaning not known). // Buffer any HttpContent except StreamContent and PushStreamContent return !(content is StreamContent || content is PushStreamContent); } return false; } ```