Remove the concept of document.documentElement

sky/engine/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple 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
@@ skipping 110 matching lines @@
     AtomicString mediaType() const;
     void setMediaType(const AtomicString&);
 
     void postLayoutTimerFired(Timer<FrameView>*);
 
     void paint(GraphicsContext* context, const IntRect& rect) override;
 
     bool isPainting() const;
     bool hasEverPainted() const { return m_lastPaintTime; }
 
-    Color documentBackgroundColor() const;
-
     static double currentFrameTimeStamp() { return s_currentFrameTimeStamp; }
 
     void updateLayoutAndStyleForPainting();
     void updateLayoutAndStyleIfNeededRecursive();
 
     void forceLayout(bool allowSubtree = false);
 
     // Methods to convert points and rects between the coordinate space of the renderer, and this view.
     IntRect convertFromRenderer(const RenderObject&, const IntRect&) const;
     IntRect convertToRenderer(const RenderObject&, const IntRect&) const;
@@ skipping 102 matching lines @@
     bool m_layoutSizeFixedToFrameSize;
 
     Vector<IntRect> m_tickmarks;
 };
 
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_FRAME_FRAMEVIEW_H_