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* [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
return fullscreenable_;
}
void NativeWindowViews::SetClosable(bool closable) {
#if defined(OS_WIN)
  HMENU menu = GetSystemMenu(GetAcceleratedWidget(), false);
  if (closable) {
    EnableMenuItem(menu, SC_CLOSE, MF_BYCOMMAND | MF_ENABLED);
  } else {
    EnableMenuItem(menu, SC_CLOSE, MF_BYCOMMAND | MF_DISABLED | MF_GRAYED);
  }
#endif
}
bool NativeWindowViews::IsClosable() {
#if defined(OS_WIN)
  HMENU menu = GetSystemMenu(GetAcceleratedWidget(), false);
  MENUITEMINFO info;
  memset(&info, 0, sizeof(info));
  info.cbSize = sizeof(info);
  info.fMask = MIIM_STATE;
  if (!GetMenuItemInfo(menu, SC_CLOSE, false, &info)) {
    return false;
  }
  return !(info.fState & MFS_DISABLED);
#elif defined(USE_X11)
  return true;
#endif
}
void NativeWindowViews::SetAlwaysOnTop(ui::ZOrderLevel z_order,