Clean headers in Designer.

Ran script to remove inludes on a trial-and-error basis and
manually corrected it.

Change-Id: Ia97b5bd9e4496cd824f35c5fda8ccf0db9af471c
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

src/plugins/designer/formeditorstack.cpp

@@ -30,7 +30,6 @@
 #include "formeditorstack.h"
 #include "formwindoweditor.h"
 #include "formeditorw.h"
-#include "designerconstants.h"
 
 #include <widgethost.h>
 
@@ -46,7 +45,6 @@
 #include <QDesignerPropertyEditorInterface>
 
 #include <QDebug>
-#include <QVariant>
 #include <QRect>
 
 namespace Designer {