Visit empty expressions.

ICSharpCode.NRefactory/CSharp/Parser/CSharpParser.cs

@@ -1180,6 +1180,11 @@ namespace ICSharpCode.NRefactory.CSharp
 				return result;
 			}
 			
+			public override object Visit (Mono.CSharp.EmptyExpression emptyExpression)
+			{
+				return new ICSharpCode.NRefactory.CSharp.EmptyExpression (Convert (emptyExpression.Location));
+			}
+			
 			public override object Visit (EmptyExpressionStatement emptyExpressionStatement)
 			{
 				return new EmptyExpression (Convert (emptyExpressionStatement.Location));

ICSharpCode.NRefactory/CSharp/Parser/mcs/expression.cs

@@ -8803,7 +8803,7 @@ namespace Mono.CSharp
 	///   This is also now used as a placeholder where a no-action expression
 	///   is needed (the `New' class).
 	/// </summary>
-	class EmptyExpression : Expression
+	public class EmptyExpression : Expression
 	{
 		sealed class OutAccessExpression : EmptyExpression
 		{
@@ -8855,6 +8855,11 @@ namespace Mono.CSharp
 		public override void EmitSideEffect (EmitContext ec)
 		{
 		}
+		
+		public override object Accept (StructuralVisitor visitor)
+		{
+			return visitor.Visit (this);
+		}
 	}
 	
 	//

ICSharpCode.NRefactory/CSharp/Parser/mcs/visit.cs

@@ -178,6 +178,11 @@ namespace Mono.CSharp
 		{
 			return null;
 		}
+		
+		public virtual object Visit (EmptyExpression emptyExpression)
+		{
+			return null;
+		}
 
 		public virtual object Visit (If ifStatement)
 		{