Revert "[kstyle] Implement application unpolish to delete ShadowHelper"

This reverts commit a0433d089a.

This causes quite some problems when a style sheet is used.

kstyle/breezestyle.cpp

@@ -197,24 +197,9 @@ namespace Breeze
 
     //______________________________________________________________
     Style::~Style( void )
-    {
-        cleanup();
-    }
-
-    //______________________________________________________________
-    void Style::unpolish( QApplication* )
-    {
-        // NOTE: unpolish is not called in general on tear-down of Application
-        // only when a new QStyle is loaded by the QApplication unpolish is invoked
-        cleanup();
-    }
-
-    void Style::cleanup( void )
     {
         delete _shadowHelper;
-        _shadowHelper = nullptr;
         delete _helper;
-        _helper = nullptr;
     }
 
     //______________________________________________________________

kstyle/breezestyle.h

@@ -92,6 +92,7 @@ namespace Breeze
 
         //* needed to avoid warnings at compilation time
         using  ParentStyleClass::polish;
+        using  ParentStyleClass::unpolish;
 
         //* widget polishing
         virtual void polish( QWidget* );
@@ -99,9 +100,6 @@ namespace Breeze
         //* widget unpolishing
         virtual void unpolish( QWidget* );
 
-        //* application unpolishing
-        void unpolish( QApplication* ) override;
-
         //* polish scrollarea
         void polishScrollArea( QAbstractScrollArea* );
 
@@ -473,9 +471,6 @@ namespace Breeze
 
         private:
 
-        //* shared cleanup for unpolish and dtor
-        void cleanup();
-
         //*@name scrollbar button types (for addLine and subLine )
         //@{
         ScrollBarButtonType _addLineButtons;