Why IHttpContextAccessor resolves without registration on Debug mode from VS?

Question

I have a simple .NET Core Web API application (it is a default WebAPI template).

Startup registration class is default:

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc();
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        app.UseMvc();
    }
}

The controller is very simple also:

[Route("api/[controller]")]
public class ValuesController : Controller
{
    private readonly IHttpContextAccessor _httpContextAccessor;

    public ValuesController(IHttpContextAccessor httpContextAccessor)
    {
        _httpContextAccessor = httpContextAccessor;
    }

    [HttpGet]
    public string Get()
    {
        return _httpContextAccessor.HttpContext.TraceIdentifier;
    }
}

As you can see I have not registered IHttpContextAccessor interface on Startup.

And ValuesController works fine on Debug mode via Visual Studio 2017.

When I publish my application on IIS then I have exception.

The exception from Log file is here:

System.InvalidOperationException: Unable to resolve service for type 'Microsoft.AspNetCore.Http.IHttpContextAccessor' while attempting to activate 'HttpAccessorTest.Controllers.ValuesController'

It is absolutely correct exception because I have not registered IHttpContextAccessor as described here.

When I register IHttpContextAccessor then all works fine of course.

So my question: Why IHttpContextAccessor resolves without registration on VS2017 Debug mode?