Test - Add JS Callback test that uses ExpandoObject (SerializeV8SimpleObject now supports Expando)

Follow up to #4959

Author: amaitland

CefSharp.Test/Javascript/JavascriptCallbackTests.cs

@@ -3,6 +3,7 @@
 // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
 
 using System;
+using System.Dynamic;
 using System.Globalization;
 using System.Threading.Tasks;
 using Xunit;
@@ -207,5 +208,30 @@ public async Task ShouldEchoDateTimeNow()
 
             output.WriteLine("Expected {0} : Actual {1}", expectedDateTime, actualDateTime);
         }
+
+        [Fact]
+        public async Task ShouldWorkWithExpandoObject()
+        {
+            AssertInitialLoadComplete();
+
+            var expectedDateTime = DateTime.Now;
+
+            dynamic request = new ExpandoObject();
+            request.dateTime = expectedDateTime;
+
+            var javascriptResponse = await Browser.EvaluateScriptAsync("(function(p) { return p; })");
+            Assert.True(javascriptResponse.Success);
+
+            var callback = (IJavascriptCallback)javascriptResponse.Result;
+
+            var callbackResponse = await callback.ExecuteAsync(request);
+
+            dynamic response = callbackResponse.Result;
+            var actualDateTime = (DateTime)response.dateTime;
+
+            Assert.Equal(expectedDateTime, actualDateTime, TimeSpan.FromMilliseconds(10));
+
+            output.WriteLine("Expected {0} : Actual {1}", expectedDateTime, actualDateTime);
+        }
     }
 }