title: Enum.IsDefined returns false for strings
body: <p>I used the <code>Enum.IsDefined()</code> method for a string, but I get <code>False</code> in a situation where I think I should get <code>True</code>. Please check the below code:</p>
  
  <pre><code>public enum YourEnum : int
  {
      Zero = 0,
      One = 1
  }
  
  public class Program
  {
  
      public static void Main(string[] args)
      {
          Console.WriteLine(Enum.IsDefined(typeof(YourEnum), 1));
          Console.WriteLine(Enum.IsDefined(typeof(YourEnum), 1.ToString()));
      }
  } 
  </code></pre>
  
  <p><a href="http://rextester.com/UMNE74342" rel="nofollow noreferrer"><strong>C# Fiddle Demo</strong></a><br>
  Result:</p>
  
  <pre><code>True
  False
  </code></pre>
  
  <p>I don't know why should I get <code>False</code> in the second case. Any help is appreciated.</p>