Delete unnecessary class instances

OutlineWidgetStack inherits from QStackedWidget, so you don't need a
member object like QStackedWidget.

The m_Factory object is not used in the OutlineWidgetStack class, is
of private type, and is not available in its OutlineWidgetStack
derived class.

Change-Id: I0b94a654dde023144f01e0bd7808ad5cc1dc92b8
Reviewed-by: David Schulz <david.schulz@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/texteditor/outlinefactory.cpp

@@ -62,8 +62,6 @@ void IOutlineWidgetFactory::updateOutline()
 namespace Internal {
 
 OutlineWidgetStack::OutlineWidgetStack(OutlineFactory *factory) :
-    QStackedWidget(),
-    m_factory(factory),
     m_syncWithEditor(true),
     m_sorted(false)
 {

src/plugins/texteditor/outlinefactory.h

@@ -58,8 +58,6 @@ private:
     void updateEditor(Core::IEditor *editor);
     void updateCurrentEditor();
 
-    QStackedWidget *m_widgetStack;
-    OutlineFactory *m_factory;
     QToolButton *m_toggleSync;
     QToolButton *m_filterButton;
     QToolButton *m_toggleSort;