Imutability for macro nodes

Src/AST/Myc.Ast.JSON.pas

@@ -303,11 +303,11 @@ var
     argsArray: TJSONArray;
     arg: IAstNode;
 begin
-    calleeObj := Accept(Node.Callee);
+    calleeObj := Accept(Node.CallNode.Callee);
     bodyObj := Accept(Node.ExpandedBody);
 
     argsArray := TJSONArray.Create;
-    for arg in Node.Arguments do
+    for arg in Node.CallNode.Arguments do
         argsArray.Add(Accept(arg));
 
     Result := TJSONObject.Create;