qmlscene does not exit when run in Debugger

1. Open project qtdeclarative\examples\quick\demos\samegame\samegame.qmlproject from Qt5's repository.
2. Configure it to run in QML Scene of Qt 5.3.
3. Run the project in debugger.
4. In the app, click "1 Player".
5. In the app, click the "Power-off" button.
   QML Scene's window will close but qmlscene.exe will keep running and occupy one CPU core.

On exit, qmlscene.exe should quit just as it does when running without the debugger. With QML Scene from Qt 5.4, this seems to work correctly.