Fix under-invalidation about view background change caused by body style change

Source/core/layout/LayoutView.h

Index: Source/core/layout/LayoutView.h
diff --git a/Source/core/layout/LayoutView.h b/Source/core/layout/LayoutView.h
index 846f4f671712bc6e190e094a2eb3e02b4d279679..7a500d1d5a44b84065c59910ba9023c24d691eff 100644
--- a/Source/core/layout/LayoutView.h
+++ b/Source/core/layout/LayoutView.h
@@ -142,7 +142,7 @@ public:
     bool usesCompositing() const;
 
     IntRect unscaledDocumentRect() const;
-    LayoutRect backgroundRect(LayoutBox* backgroundRenderer) const;
+    LayoutRect backgroundRect(LayoutBox* backgroundLayoutObject) const;
 
     IntRect documentRect() const;
 
@@ -171,6 +171,8 @@ public:
     void popLayoutState() { ASSERT(m_layoutState); m_layoutState = m_layoutState->next(); }
     virtual void invalidateTreeIfNeeded(PaintInvalidationState&) override final;
 
+    LayoutObject* backgroundLayoutObject() const;
+
 private:
     virtual void mapLocalToContainer(const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = 0, const PaintInvalidationState* = 0) const override;
     virtual const LayoutObject* pushMappingToContainer(const LayoutBoxModelObject* ancestorToStopAt, LayoutGeometryMap&) const override;
@@ -186,8 +188,6 @@ private:
 
     bool shouldUsePrintingLayout() const;
 
-    LayoutObject* backgroundRenderer() const;
-
     FrameView* m_frameView;
 
     LayoutObject* m_selectionStart;