Remove unused dynamic TryGetIndex

Author: thohng

Testing.Dynamic.Json/DJsonArray.cs

@@ -1,5 +1,4 @@
 using System.Collections.Generic;
-using System.Dynamic;
 using System.Linq;
 using System.Text.Json.Serialization;
 
@@ -16,12 +15,6 @@ public class DJsonArray : DJson
 
         public override List<object> InnerList => _list;
 
-        public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, out object result)
-        {
-            result = indexes.Length == 1 && indexes[0] is int index && index >= 0 && index < _list.Count ? _list[index] : null;
-            return true;
-        }
-
         public override object this[int index] => index >= 0 && index < _list.Count ? _list[index] : null;
     }
 }