obj.IsDestroyed() method for Unity objects

ObjectExtensions.cs

public static class ObjectExtensions {
	public static bool IsDestroyed (this UnityEngine.Object obj) {
		// Returns true if the object has been destroyed;
		// false if it's actually null.
		// (You could throw a NullReferenceException instead
		// in the latter case if you wanted.)
		return obj == null && !ReferenceEquals (obj, null);
	}
}