Use reference for paintInvalidationContainer param of invalidatePaintIfNeeded

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 0bd54dfdcb619cb822836e0c3fd5b96e09eb3fc4..342abb79a431d62d0f1c6d11b42b64a0c5768214 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -842,7 +842,7 @@ public:
     // Invalidate the paint of a specific subrectangle within a given object. The rect |r| is in the object's coordinate space.
     void invalidatePaintRectangle(const LayoutRect&) const;
 
-    bool invalidatePaintIfNeeded(const RenderLayerModelObject* paintInvalidationContainer,
+    bool invalidatePaintIfNeeded(const RenderLayerModelObject& paintInvalidationContainer,
         const LayoutRect& oldBounds, const LayoutPoint& oldPositionFromPaintInvalidationContainer);
 
     // Walk the tree after layout issuing paint invalidations for renderers that have changed or moved, updating bounds that have changed, and clearing paint invalidation state.
@@ -1088,11 +1088,11 @@ protected:
     // of this renderer within the current layer that should be used for each result.
     virtual void computeSelfHitTestRects(Vector<LayoutRect>&, const LayoutPoint& layerOffset) const { };
 
-    virtual InvalidationReason getPaintInvalidationReason(const RenderLayerModelObject* paintInvalidationContainer,
+    virtual InvalidationReason getPaintInvalidationReason(const RenderLayerModelObject& paintInvalidationContainer,
         const LayoutRect& oldBounds, const LayoutPoint& oldPositionFromPaintInvalidationContainer,
         const LayoutRect& newBounds, const LayoutPoint& newPositionFromPaintInvalidationContainer);
-    virtual void incrementallyInvalidatePaint(const RenderLayerModelObject* paintInvalidationContainer, const LayoutRect& oldBounds, const LayoutRect& newBounds);
-    void fullyInvalidatePaint(const RenderLayerModelObject* paintInvalidationContainer, InvalidationReason, const LayoutRect& oldBounds, const LayoutRect& newBounds);
+    virtual void incrementallyInvalidatePaint(const RenderLayerModelObject& paintInvalidationContainer, const LayoutRect& oldBounds, const LayoutRect& newBounds);
+    void fullyInvalidatePaint(const RenderLayerModelObject& paintInvalidationContainer, InvalidationReason, const LayoutRect& oldBounds, const LayoutRect& newBounds);
 
 private:
     const RenderLayerModelObject* enclosingCompositedContainer() const;