title: CallerMemberName in .NET 4.0 not working
body: <p>I am trying to use <code>CallerMemberName</code> attribute in .NET 4.0 via BCL portability pack. It is always returning an empty string instead of the member name. What am I doing wrong?</p>
  
  <pre><code>public partial class Form1 : Form
  {
      public Form1()
      {
          InitializeComponent();
          MessageBox.Show(new class2().CallMe);
      }
  }
  
  public class class2
  {
      public string CallMe 
      {
          get
          {
              return HelpMe();
          }
      }
  
      private string HelpMe([CallerMemberName] string param = "")
      {
          return param;
      }
  }
  </code></pre>