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

Source/core/dom/NodeRenderingTraversal.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 22 matching lines @@
 #include "core/rendering/RenderObject.h"
 
 namespace WebCore {
 
 namespace NodeRenderingTraversal {
 
 static bool isRendererReparented(const RenderObject* renderer)
 {
     if (!renderer->node()->isElementNode())
         return false;
-    if (renderer->style() && !renderer->style()->flowThread().isEmpty())
-        return true;
     if (toElement(renderer->node())->isInTopLayer())
         return true;
     return false;
 }
 
 void ParentDetails::didTraverseInsertionPoint(const InsertionPoint* insertionPoint)
 {
     if (!m_insertionPoint) {
         m_insertionPoint = insertionPoint;
         m_resetStyleInheritance  = m_resetStyleInheritance || insertionPoint->resetStyleInheritance();
@@ skipping 95 matching lines @@
     for (size_t i = position + 1; i < topLayerElements.size(); ++i) {
         if (RenderObject* renderer = topLayerElements[i]->renderer())
             return renderer;
     }
     return 0;
 }
 
 }
 
 } // namespace