title: Using ReplaceChild in HtmlAgilityPack in WinRT
body: <p>I'm trying to convert HTML to markdown in a windows store app. The following code works in a .NET 4 MVC project</p>
  
  <pre><code>HtmlDocument doc = new HtmlDocument();
  doc.LoadHtml(html); 
  
  foreach (var x in doc.DocumentNode.SelectNodes("//strong"))
  {
      x.ParentNode.ReplaceChild(
              HtmlAgilityPack.HtmlNode.CreateNode("**" + x.InnerHtml + "**"),
      x);
  }
  </code></pre>
  
  <p><code>SelectNodes</code> is not available in the WinRT build so when porting the code I replaced this with Descendants. </p>
  
  <pre><code>foreach (var x in doc.DocumentNode.Descendants("//strong"))
  {
      x.ParentNode.ReplaceChild(
              HtmlAgilityPack.HtmlNode.CreateNode("**" + x.InnerHtml + "**"),
      x);
  }
  </code></pre>
  
  <p>This code leaves the HtmlDocument unchanged. Am I doing something wrong, or is this a bug? </p>