Remove the concept of document.documentElement

sky/engine/core/rendering/RenderBoxModelObject.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 228 matching lines @@
     bool borderObscuresBackground() const;
     RoundedRect backgroundRoundedRectAdjustedForBleedAvoidance(GraphicsContext*, const LayoutRect&, BackgroundBleedAvoidance, InlineFlowBox*, const LayoutSize&, bool includeLogicalLeftEdge, bool includeLogicalRightEdge) const;
     LayoutRect borderInnerRectAdjustedForBleedAvoidance(GraphicsContext*, const LayoutRect&, BackgroundBleedAvoidance) const;
 
     LayoutRect localCaretRectForEmptyElement(LayoutUnit width, LayoutUnit textIndentOffset);
 
     static void clipRoundedInnerRect(GraphicsContext*, const LayoutRect&, const RoundedRect& clipRect);
 
     bool hasAutoHeightOrContainingBlockWithAutoHeight() const;
 
-    bool isDocumentElementWithOpaqueBackground() const;
-
     void paintRootBackgroundColor(const PaintInfo&, const LayoutRect&, const Color&);
 
 public:
     static bool shouldAntialiasLines(GraphicsContext*);
 
     // These functions are only used internally to manipulate the render tree structure via remove/insert/appendChildNode.
     void moveChildTo(RenderBoxModelObject* toBoxModelObject, RenderObject* child, RenderObject* beforeChild, bool fullRemoveInsert);
     void moveAllChildrenTo(RenderBoxModelObject* toBoxModelObject, RenderObject* beforeChild, bool fullRemoveInsert);
 
     IntSize calculateImageIntrinsicDimensions(StyleImage*, const IntSize& scaledPositioningAreaSize) const;
@@ skipping 21 matching lines @@
     void drawBoxSideFromPath(GraphicsContext*, const LayoutRect&, const Path&, const class BorderEdge[],
                             float thickness, float drawThickness, BoxSide, const RenderStyle*,
                             Color, EBorderStyle, BackgroundBleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge);
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderBoxModelObject, isBoxModelObject());
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_RENDERING_RENDERBOXMODELOBJECT_H_