[dotnet] Send data over cdp consecutively (#12666)

Send data over cdp consecutively

Author: nvborisenko

dotnet/src/webdriver/DevTools/WebSocketConnection.cs

@@ -37,6 +37,7 @@ public class WebSocketConnection
         private Task dataReceiveTask;
         private bool isActive = false;
         private ClientWebSocket client = new ClientWebSocket();
+        private readonly SemaphoreSlim sendMethodSemaphore = new SemaphoreSlim(1, 1);
 
         /// <summary>
         /// Initializes a new instance of the <see cref="WebSocketConnection" /> class.
@@ -159,7 +160,17 @@ public virtual async Task SendData(string data)
         {
             ArraySegment<byte> messageBuffer = new ArraySegment<byte>(Encoding.UTF8.GetBytes(data));
             this.Log($"SEND >>> {data}");
-            await this.client.SendAsync(messageBuffer, WebSocketMessageType.Text, endOfMessage: true, CancellationToken.None);
+
+            await sendMethodSemaphore.WaitAsync().ConfigureAwait(false);
+
+            try
+            {
+                await this.client.SendAsync(messageBuffer, WebSocketMessageType.Text, endOfMessage: true, CancellationToken.None);
+            }
+            finally
+            {
+                sendMethodSemaphore.Release();
+            }
         }
 
         /// <summary>