こうなる?
public class Singleton extends MonoBehaviour { protected static var instance : MonoBehaviour; /** Returns the instance of this singleton. */ public static function get Instance() : MonoBehaviour { if( instance == null ) { instance = FindObjectOfType(MonoBehaviour) as MonoBehaviour; if( instance == null ) { Debug.LogError("An instance of " + typeof(MonoBehaviour) + " is needed in the scene, but there is none."); } } return instance; } }