TextEditor: move setIfdefedOutBlocks to TextDocument

The location of the blocks to marked ifdefed out are not tied to a
specific editor instance, but just depend on the document content.

Change-Id: I837730dc00e1d6060dd46bbb2cfccbfa5f72e6ce
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/texteditor/texteditor.h

@@ -331,9 +331,6 @@ public:
     RefactorMarkers refactorMarkers() const;
     void setRefactorMarkers(const RefactorMarkers &markers);
 
-    // the blocks list must be sorted
-    void setIfdefedOutBlocks(const QList<BlockRange> &blocks);
-
     enum Side { Left, Right };
     QAction *insertExtraToolBarWidget(Side side, QWidget *widget);