[DO NOT COMMIT] Don't keep pointers to table sections when told to recalculate sections.

third_party/WebKit/Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 2305 matching lines @@
     if (parent == ancestorToStopAt)
       break;
   }
   rect.move(-offsetFromContainer);
 }
 
 bool LayoutBox::mapToVisualRectInAncestorSpace(
     const LayoutBoxModelObject* ancestor,
     LayoutRect& rect,
     VisualRectFlags visualRectFlags) const {
+  DCHECK(!needsLayout());
   inflateVisualRectForFilter(rect);
 
   if (ancestor == this)
     return true;
 
   bool ancestorSkipped;
   bool filterSkipped;
   LayoutObject* container =
       this->container(ancestor, &ancestorSkipped, &filterSkipped);
   LayoutBox* tableRowContainer = nullptr;
@@ skipping 3353 matching lines @@
     block->adjustChildDebugRect(rect);
 
   return rect;
 }
 
 bool LayoutBox::shouldClipOverflow() const {
   return hasOverflowClip() || styleRef().containsPaint() || hasControlClip();
 }
 
 }  // namespace blink