title: System.Web.HttpContext in .NET Standard
body: <p>I'm developing a .NET Standard 2.0 class library in Visual Studio 2017 15.5 which at some point tries to call a Web Service.
  The way to authenticate is by using WSE 3.0 (Microsoft.Web.Services3).</p>
  
  <p>Before the call, it crashes executing this instruction:</p>
  
  <pre><code>UsernameToken userToken = new UsernameToken(sUser, sPass, PasswordOption.SendHashed);
  </code></pre>
  
  <p>The error is:</p>
  
  <pre><code>Could not load type 'System.Web.HttpContext' from assembly 'System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.
  </code></pre>
  
  <p>Does <strong>System.Web.HttpContext</strong> exist in .NET Standard? How can I solve this?</p>