Fix const correctness of containerForRepaint

Source/core/rendering/RenderObject.h

Index: Source/core/rendering/RenderObject.h
diff --git a/Source/core/rendering/RenderObject.h b/Source/core/rendering/RenderObject.h
index bbd53eedf4cffd918e1f61829cb4e775fa519cde..700edf880d38d1b268a4193ebb64c44f80b7b3bc 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -813,7 +813,7 @@ public:
     // Return the RenderLayerModelObject in the container chain which is responsible for painting this object, or 0
     // if painting is root-relative. This is the container that should be passed to the 'forRepaint'
     // methods.
-    RenderLayerModelObject* containerForRepaint() const;
+    const RenderLayerModelObject* containerForRepaint() const;
 
     // Actually do the repaint of rect r for this object which has been computed in the coordinate space
     // of repaintContainer. If repaintContainer is 0, repaint via the view.
@@ -828,7 +828,7 @@ public:
 
     // Repaint only if our old bounds and new bounds are different. The caller may pass in newBounds if they are known.
     bool repaintAfterLayoutIfNeeded(const RenderLayerModelObject* repaintContainer, bool wasSelfLayout,
-        const LayoutRect& oldBounds, const LayoutPoint& oldPositionFromRepaintContainer, const LayoutRect* newBoundsPtr = 0, const LayoutPoint* newPositionFromRepaintContainer = 0);
+        const LayoutRect& oldBounds, const LayoutPoint& oldPositionFromRepaintContainer, const LayoutRect* newBoundsPtr = 0, const LayoutPoint* newPositionFromRepaintContainer = 0) const;

[Julien - ping for review, 2014/05/07 22:55:42]

I am on the fence about that. While it is true that we don't modify RenderObject
in this function now, it doesn't mean that we won't in the future or that it's
wrong in the long run.

If that's not required by some of your 'const' change, I would just ignore that
part for now.

 
     // Walk the tree after layout repainting renderers that have changed or moved, updating bounds that have changed, and clearing repaint state.
     virtual void repaintTreeAfterLayout();