### Preflight Checklist

* [x] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
* [x] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
* [x] I have searched the issue tracker for an issue that matches the one I want to file, without success.

### Issue Details

It would appear that `app.focus()` stopped working in Electron 6, and remains broken in Electron 8.

* **Electron Version:**
  * 8.0.3
* **Operating System:**
  * macOS
* **Last Known Working Electron version:**
  * 5.0.13

### Expected Behavior
`app.focus()` should bring the application to the foreground.

### Actual Behavior
`app.focus()` does nothing.

### To Reproduce

Fiddle: https://gist.github.com/a772265b312329e3f3bc1feb7b6aff7d

1) Start this fiddle.
2) As soon as the window pops up, select another application so that Electron is in the background.
3) Within 5 seconds, the app will attempt to focus itself to no avail.

shell/browser/browser_linux.cc
if (error != nullptr) {
      g_warning("%s", error->message);
      g_clear_error(&error);
    } else {
      gtk_about_dialog_set_logo(dialog, icon);
      g_clear_object(&icon);
    }
  }
  if ((val = opts.FindListKey("authors"))) {
    std::vector<const char*> cstrs;
    for (const auto& authorVal : val->GetList()) {
      if (authorVal.is_string()) {
        cstrs.push_back(authorVal.GetString().c_str());
      }
    }
    if (cstrs.empty()) {
      LOG(WARNING) << "No author strings found in 'authors' array";
    } else {
      cstrs.push_back(nullptr);  
      gtk_about_dialog_set_authors(dialog, cstrs.data());
    }
  }
  gtk_dialog_run(GTK_DIALOG(dialog));
  gtk_widget_destroy(dialogWidget);
}
void Browser::SetAboutPanelOptions(base::DictionaryValue options) {
  about_panel_options_ = std::move(options);
}
}