Comment 8 for bug 1337244

Though, the Unity code doesn't seem to use HSplitter or VSplitter. Also, it doesn't call QueueRelayout on any InputArea objects, which seems to be the only other way for an InputArea object to be put on the layout queue. Btw the "parent object of an object of type InputArea is a Layout object" comment at Area.cpp:603 is indeed wrong, since UnityWindowView::GetBoundingArea() has a counterexample.