Refactor root element background painting

Source/core/layout/LayoutObject.h

Index: Source/core/layout/LayoutObject.h
diff --git a/Source/core/layout/LayoutObject.h b/Source/core/layout/LayoutObject.h
index cb1c712f132fe869ae6f4793e744140162dd40c2..c1a6cd22fa4253e5995d423ae7f0c27c1bb077e3 100644
--- a/Source/core/layout/LayoutObject.h
+++ b/Source/core/layout/LayoutObject.h
@@ -1005,9 +1005,6 @@ public:
     // Compute a list of hit-test rectangles per layer rooted at this layoutObject.
     virtual void computeLayerHitTestRects(LayerHitTestRects&) const;
 
-    // Return the layoutObject whose background style is used to paint the root background. Should only be called on the layoutObject for which isDocumentElement() is true.
-    LayoutObject* layoutObjectForRootBackground();
-
     RespectImageOrientationEnum shouldRespectImageOrientation() const;
 
     bool isRelayoutBoundaryForInspector() const;