Skip a flaky Windows/canvaskit test in hot_reload_web_test.dart (#85044)

* Update hot_reload_web_test.dart

For https://github.com/flutter/flutter/issues/85043

* Add missing import

packages/flutter_tools/test/web.shard/hot_reload_web_test.dart

@@ -5,6 +5,7 @@
 // @dart = 2.8
 
 import 'dart:async';
+import 'dart:io';
 
 import 'package:file/file.dart';
 
@@ -70,5 +71,5 @@ void main() {
     } finally {
       await subscription.cancel();
     }
-  });
+  }, skip: Platform.isWindows); // Skipping for https://github.com/flutter/flutter/issues/85043
 }