FeatureCache is over-checked and over-reset

[benaadams]

A simple plantext middleware as below, will check the Frame IFeatureCollection 7 times and initialize/reset the Context, Resquest and Responses feature caches twice each.

public static Task WriteResponse(HttpResponse response)
{
    var payloadLength = _helloWorldPayload.Length;
    response.StatusCode = 200;
    response.ContentType = "text/plain";
    response.ContentLength = payloadLength;
    return response.Body.WriteAsync(_helloWorldPayload, 0, payloadLength);
}

The extra reset and checks are from initalization; then reinitialization after RequestServicesFeature is added to the collection by the host, increasing the IFeatureCollection's version count.

[muratg]

@davidfowl thoughts? (PR is assigned to you too.)

[aspnet-hello]

This issue was moved to dotnet/aspnetcore#2693