flutter_driver pauses all isolates at their startup (even ones started from compute()), rather than only pausing initial isolate #24703

Isolates spawned using "compute" don't execute properly while executed in an integration test which in turn results in incorrect app behavior.
How to reproduce:

• use example from https://flutter.io/docs/cookbook/testing/integration
• in lib/main.dart

1. add:

import 'package:flutter/foundation.dart';

2. add function:

String _test(String s) {
  return s;
}

3. modify _incrementCounter function:

  void _incrementCounter() async {
    final s = await compute(_test, 'hello');
    print(s);

    setState(() {
      _counter++;
    });
  }

The app works properly when executing flutter run, but the integration test fails (flutter drive --target=test_driver/app.dart)