title: Deserialize entire FlowDocument issue
body: <p>I have the following string </p>
  
  <pre><code>&lt;FlowDocument xml:space="preserve" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"&gt;&lt;Paragraph&gt;Some text &lt;LineBreak /&gt;&lt;LineBreak /&gt; &lt;Run FontWeight="bold"&gt;Text ...&lt;/Run&gt;&lt;LineBreak /&gt;sjhfdjsgfjsd &lt;LineBreak /&gt;&lt;LineBreak /&gt; &lt;Run FontWeight="bold"&gt;Text 2 &lt;/Run&gt;&lt;LineBreak /&gt;sdkfskfjsf &lt;LineBreak /&gt;&lt;LineBreak /&gt; &lt;/Paragraph&gt;&lt;/FlowDocument&gt;
  </code></pre>
  
  <p>And I try to use this code to deserialize it into FlowDocument but no success.</p>
  
  <p>Any clue what I am missing?</p>
  
  <p>Thank you!</p>
  
  <p><strong>CODE</strong></p>
  
  <pre><code> StringReader stringReader = new StringReader(xamlString);
   XmlReader xmlReader = XmlReader.Create(stringReader);
   Section sec = XamlReader.Load(xmlReader) as Section;
   FlowDocument doc = new FlowDocument();
   while (sec.Blocks.Count &gt; 0)
     doc.Blocks.Add(sec.Blocks.FirstBlock);
   return doc;
  </code></pre>