title: PrivateFontCollection Families are not reliable with more iterations
body: <p>I've load the MemoryStream to a PrivateFontCollection and print the Font-Family count.  </p>
  
  <p>I've done these process for 10 times and I want the same output for every iteration. I want correct output for two iterations and sometimes the first iteration is also going wrong. I can't have a consistent output.</p>
  
  <p>Provide me a solution to have a consistent output using PrivateFontCollection.<br>
  <strong>Note:</strong> Fonts folder contains 5 different fonts.</p>
  
  <pre><code>private static void Work()
  {
      string fontPath = @"D:\fonts";
      PrivateFontCollection fontCollection = null;
      for (int i = 1; i &lt; 11; i++)
      {
          var fileList = Directory.GetFiles(fontPath, "*.ttf", SearchOption.TopDirectoryOnly);
          fontCollection = SafeLoadFontFamily(fileList);
          Console.WriteLine(i+" Iteration and families count:"+fontCollection.Families.Length);
          fontCollection.Dispose();
      }
      Console.ReadKey();
  }
  private static PrivateFontCollection SafeLoadFontFamily(IEnumerable&lt;string&gt; fontList)
  {
      if (fontList == null) return null;
      var fontCollection = new PrivateFontCollection();
  
      foreach (string fontFile in fontList)
      {
          if (!File.Exists(fontFile)) continue;
          byte[] fontBytes = File.ReadAllBytes(fontFile);
          var fontData = Marshal.AllocCoTaskMem(fontBytes.Length);
          Marshal.Copy(fontBytes, 0, fontData, fontBytes.Length);
          fontCollection.AddMemoryFont(fontData, fontBytes.Length);
      }
      return fontCollection;
  }
  </code></pre>
  
  <p>Expected output for 10 times:<br/>
  1 Iteration and families count:5<br/>
  2 Iteration and families count:5<br/>
  3 Iteration and families count:5<br/>
  4 Iteration and families count:5<br/>
  5 Iteration and families count:5<br/>
  6 Iteration and families count:5<br/>
  7 Iteration and families count:5<br/>
  8 Iteration and families count:5<br/>
  9 Iteration and families count:5<br/>
  10 Iteration and families count:5<br/></p>
  
  <p>Actual output:[ inconsistent output] <br>
  1 Iteration and families count:5<br>
  2 Iteration and families count:5<br>
  3 Iteration and families count:5<br>
  4 Iteration and families count:5<br>
  5 Iteration and families count:4<br>
  6 Iteration and families count:3<br>
  7 Iteration and families count:3<br>
  8 Iteration and families count:4<br>
  9 Iteration and families count:4<br>
  10 Iteration and families count:4<br></p>