[browser] Fix double dispose of GCHandle in BrowserWebSocket (#113464)

Co-authored-by: pavelsavara <[email protected]>

Author: filipnavara

src/libraries/System.Net.WebSockets.Client/src/System/Net/WebSockets/BrowserWebSockets/BrowserWebSocket.cs

@@ -399,7 +399,7 @@ private async Task SendAsyncCore(ArraySegment<byte> buffer, WebSocketMessageType
 
                 if (sendTask != null)  // this is optimization for single-threaded build, see resolvedPromise() in web-socket.ts. Null means synchronously resolved.
                 {
-                    await CancellationHelper(sendTask, cancellationToken, previousState, pinBuffer).ConfigureAwait(false);
+                    await CancellationHelper(sendTask, cancellationToken, previousState).ConfigureAwait(false);
                 }
             }
             catch (JSException ex)
@@ -442,7 +442,7 @@ private async Task<WebSocketReceiveResult> ReceiveAsyncCore(ArraySegment<byte> b
 
                 if (receiveTask != null)  // this is optimization for single-threaded build, see resolvedPromise() in web-socket.ts. Null means synchronously resolved.
                 {
-                    await CancellationHelper(receiveTask, cancellationToken, previousState, pinBuffer).ConfigureAwait(false);
+                    await CancellationHelper(receiveTask, cancellationToken, previousState).ConfigureAwait(false);
                 }
 
                 return ConvertResponse();
@@ -550,13 +550,12 @@ private async Task CloseAsyncCore(WebSocketCloseStatus closeStatus, string? stat
             }
         }
 
-        private async Task CancellationHelper(Task promise, CancellationToken cancellationToken, WebSocketState previousState, IDisposable? disposable = null)
+        private async Task CancellationHelper(Task promise, CancellationToken cancellationToken, WebSocketState previousState)
         {
             try
             {
                 if (promise.IsCompletedSuccessfully)
                 {
-                    disposable?.Dispose();
                     return;
                 }
                 if (promise.IsCompleted)
@@ -602,10 +601,6 @@ private async Task CancellationHelper(Task promise, CancellationToken cancellati
                     throw new WebSocketException(WebSocketError.NativeError, ex);
                 }
             }
-            finally
-            {
-                disposable?.Dispose();
-            }
         }
 
         // needs to be called with locked _lockObject