Make use of LookupContext to find the right class.
Task-number: QTCREATORBUG-10348
Change-Id: I7f8ec769ff2239d5123726e562a1bd430f8c4567
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>