* [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

* **Electron Version:** 6.0.0-beta.13
* **Operating System:** Windows 10

### Expected Behavior

When calling `browserWindow.setAlwaysOnTop(true)`, I expect the `always-on-top-changed` event to be called with the boolean `isAlwaysOnTop` parameter set to `true`, and vice versa.

### Actual Behavior

I experience the opposite of above: When calling `browserWindow.setAlwaysOnTop(true)`, my `always-on-top-changed` handler is called with `false`, and vice versa.

### To Reproduce

I don't have any JS code to share and I'm not a JS dev (I use F# and compile to JS with Fable). I think the issue should be easy to reproduce though.
shell/browser/native_window_views.cc
if (is_modal() && NativeWindow::parent())
    static_cast<NativeWindowViews*>(parent())->DecrementChildModals();
  widget()->Hide();
  NotifyWindowHide();
#if defined(USE_X11)
  if (global_menu_bar_)
    global_menu_bar_->OnWindowUnmapped();
#endif
}
bool NativeWindowViews::IsVisible() {
  return widget()->IsVisible();
}
bool NativeWindowViews::IsEnabled() {
#if defined(OS_WIN)
  return ::IsWindowEnabled(GetAcceleratedWidget());
#elif defined(USE_X11)
  return !event_disabler_.get();
#endif
}
void NativeWindowViews::IncrementChildModals() {
  num_modal_children_++;
  SetEnabledInternal(ShouldBeEnabled());
}
void NativeWindowViews::DecrementChildModals() {
  if (num_modal_children_ > 0) {
    num_modal_children_--;
  }
  SetEnabledInternal(ShouldBeEnabled());
}
void NativeWindowViews::SetEnabled(bool enable) {