Remove unused isLayoutRoot method

Source/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 90 matching lines @@
     void setContentsSize(const IntSize&);
     IntPoint clampOffsetAtScale(const IntPoint& offset, float scale) const;
 
     void layout();
     bool didFirstLayout() const;
     void scheduleRelayout();
     void scheduleRelayoutOfSubtree(LayoutObject*);
     bool layoutPending() const;
     bool isInPerformLayout() const;
 
-    bool isLayoutRoot(const LayoutObject&) const;
     void clearLayoutSubtreeRoot(const LayoutObject&);
     int layoutCount() const { return m_layoutCount; }
 
     void countObjectsNeedingLayout(unsigned& needsLayoutObjects, unsigned& totalObjects, bool& isPartial);
 
     bool needsLayout() const;
     void setNeedsLayout();
 
     void setNeedsUpdateWidgetPositions() { m_needsUpdateWidgetPositions = true; }
 
@@ skipping 745 matching lines @@
     static const unsigned visualPixelThreshold = 32 * 32;
     if (m_visuallyNonEmptyPixelCount > visualPixelThreshold)
         setIsVisuallyNonEmpty();
 }
 
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 
 } // namespace blink
 
 #endif // FrameView_h