Constify the rendering/ selection code

Source/core/rendering/RenderObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 903 matching lines @@
 
     // The current selection state for an object.  For blocks, the state refers to the state of the leaf
     // descendants (as described above in the SelectionState enum declaration).
     SelectionState selectionState() const { return m_bitfields.selectionState(); }
     virtual void setSelectionState(SelectionState state) { m_bitfields.setSelectionState(state); }
     inline void setSelectionStateIfNeeded(SelectionState);
     bool canUpdateSelectionOnRootLineBoxes();
 
     // A single rectangle that encompasses all of the selected objects within this object.  Used to determine the tightest
     // possible bounding box for the selection. The rect returned is in the coordinate space of the paint invalidation container's backing.
-    virtual LayoutRect selectionRectForPaintInvalidation(const RenderLayerModelObject* /*paintInvalidationContainer*/, bool /*clipToVisibleContent*/ = true) { return LayoutRect(); }
+    virtual LayoutRect selectionRectForPaintInvalidation(const RenderLayerModelObject* /*paintInvalidationContainer*/, bool /*clipToVisibleContent*/ = true) const { return LayoutRect(); }
 
     virtual bool canBeSelectionLeaf() const { return false; }
     bool hasSelectedChildren() const { return selectionState() != SelectionNone; }
 
     bool isSelectable() const;
     // Obtains the selection colors that should be used when painting a selection.
     Color selectionBackgroundColor() const;
     Color selectionForegroundColor() const;
     Color selectionEmphasisMarkColor() const;
 
@@ skipping 627 matching lines @@
 void showTree(const blink::RenderObject*);
 void showLineTree(const blink::RenderObject*);
 void showRenderTree(const blink::RenderObject* object1);
 // We don't make object2 an optional parameter so that showRenderTree
 // can be called from gdb easily.
 void showRenderTree(const blink::RenderObject* object1, const blink::RenderObject* object2);
 
 #endif
 
 #endif // RenderObject_h