Revert commit# 415577 "Add grid/flex layout support for <fieldset>"

third_party/WebKit/Source/core/layout/LayoutFlexibleBox.h

 /*
  * Copyright (C) 2011 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 47 matching lines @@
       LinePositionMode = PositionOnContainingLine) const override;
   int firstLineBoxBaseline() const override;
   int inlineBlockBaseline(LineDirectionMode) const override;
   IntSize originAdjustmentForScrollbars() const override;
   bool hasTopOverflow() const override;
   bool hasLeftOverflow() const override;
 
   void paintChildren(const PaintInfo&, const LayoutPoint&) const final;
 
   bool isHorizontalFlow() const;
-  virtual LayoutObject* layoutSpecialExcludedChild(bool relayoutChildren,
-                                                   SubtreeLayoutScope&) {
-    return nullptr;
-  }
 
   const OrderIterator& orderIterator() const { return m_orderIterator; }
 
   LayoutUnit crossSizeForPercentageResolution(const LayoutBox& child);
   LayoutUnit mainSizeForPercentageResolution(const LayoutBox& child);
   LayoutUnit childLogicalHeightForPercentageResolution(const LayoutBox& child);
 
   void clearCachedMainSizeForChild(const LayoutBox& child);
 
   LayoutUnit staticMainAxisPositionForPositionedChild(const LayoutBox& child);
@@ skipping 176 matching lines @@
 
   // This is SizeIsUnknown outside of layoutBlock()
   mutable SizeDefiniteness m_hasDefiniteHeight;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutFlexibleBox, isFlexibleBox());
 
 }  // namespace blink
 
 #endif  // LayoutFlexibleBox_h