Remove hack with TLW focus reset from wxWindowMSW dtor

This shouldn't be needed any more, after the previous commit which
replaces the raw pointer to the focused child in wxTopLevelWindowMSW
with a safe weak reference.

src/msw/window.cpp

@@ -405,30 +405,9 @@ wxWindowMSW::~wxWindowMSW()
 {
     SendDestroyEvent();
 
-#ifndef __WXUNIVERSAL__
-    // VS: make sure there's no wxFrame with last focus set to us:
-    for ( wxWindow *win = GetParent(); win; win = win->GetParent() )
-    {
-        wxTopLevelWindow *frame = wxDynamicCast(win, wxTopLevelWindow);
-        if ( frame )
-        {
-            if ( frame->GetLastFocus() == this )
-            {
-                frame->SetLastFocus(NULL);
-            }
-
-            // apparently sometimes we can end up with our grand parent
-            // pointing to us as well: this is surely a bug in focus handling
-            // code but it's not clear where it happens so for now just try to
-            // fix it here by not breaking out of the loop
-            //break;
-        }
-    }
-#endif // __WXUNIVERSAL__
-
     // VS: destroy children first and _then_ detach *this from its parent.
     //     If we did it the other way around, children wouldn't be able
-    //     find their parent frame (see above).
+    //     find their parent frame.
     DestroyChildren();
 
     if ( m_hWnd )