Remove CSS regions support, keeping a bare minimum to support "region-based" multicol.

Source/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 168 matching lines @@
     virtual LayoutUnit lineHeight(bool firstLine, LineDirectionMode, LinePositionMode = PositionOnContainingLine) const = 0;
     virtual int baselinePosition(FontBaseline, bool firstLine, LineDirectionMode, LinePositionMode = PositionOnContainingLine) const = 0;
 
     virtual void mapAbsoluteToLocalPoint(MapCoordinatesFlags, TransformState&) const OVERRIDE;
     virtual const RenderObject* pushMappingToContainer(const RenderLayerModelObject* ancestorToStopAt, RenderGeometryMap&) const OVERRIDE;
 
     void highQualityRepaintTimerFired(Timer<RenderBoxModelObject>*);
 
     virtual void setSelectionState(SelectionState) OVERRIDE;
 
-    bool canHaveBoxInfoInRegion() const { return !isFloating() && !isReplaced() && !isInline() && !hasColumns() && !isTableCell() && isRenderBlock() && !isSVG(); }
-
     void contentChanged(ContentChangeType);
     bool hasAcceleratedCompositing() const;
 
     virtual void computeLayerHitTestRects(LayerHitTestRects&) const OVERRIDE;
 
 protected:
     virtual void willBeDestroyed() OVERRIDE;
 
     class BackgroundImageGeometry {
     public:
@@ skipping 130 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 WebCore
 
 #endif // RenderBoxModelObject_h