Remove language version from spawnHybrid code (dart-lang/web_socket_channel#232)
The code is compatible with null safety without any changes.
diff --git a/pkgs/web_socket_channel/test/html_test.dart b/pkgs/web_socket_channel/test/html_test.dart
index 3a89098..f7ec4d9 100644
--- a/pkgs/web_socket_channel/test/html_test.dart
+++ b/pkgs/web_socket_channel/test/html_test.dart
@@ -16,7 +16,6 @@
late int port;
setUpAll(() async {
final channel = spawnHybridCode(r'''
- // @dart=2.7
import 'dart:io';
import 'package:stream_channel/stream_channel.dart';