Store :last/first-child state as restyle flags.

Source/core/rendering/style/RenderStyle.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * 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
@@ skipping 211 matching lines @@
                 && styleType == other.styleType
                 && affectedByFocus == other.affectedByFocus
                 && affectedByHover == other.affectedByHover
                 && affectedByActive == other.affectedByActive
                 && affectedByDrag == other.affectedByDrag
                 && pseudoBits == other.pseudoBits
                 && unicodeBidi == other.unicodeBidi
                 && explicitInheritance == other.explicitInheritance
                 && unique == other.unique
                 && emptyState == other.emptyState
-                && firstChildState == other.firstChildState
-                && lastChildState == other.lastChildState
                 && isLink == other.isLink;
         }
 
         bool operator!=(const NonInheritedFlags& other) const { return !(*this == other); }
 
         unsigned effectiveDisplay : 5; // EDisplay
         unsigned originalDisplay : 5; // EDisplay
         unsigned overflowX : 3; // EOverflow
         unsigned overflowY : 3; // EOverflow
         unsigned verticalAlign : 4; // EVerticalAlign
@@ skipping 12 matching lines @@
         unsigned pageBreakBefore : 2; // EPageBreak
         unsigned pageBreakAfter : 2; // EPageBreak
         unsigned pageBreakInside : 2; // EPageBreak
 
         unsigned styleType : 6; // PseudoId
         unsigned pseudoBits : 8;
         unsigned explicitInheritance : 1; // Explicitly inherits a non-inherited property
         unsigned unique : 1; // Style can not be shared.
 
         unsigned emptyState : 1;
-        unsigned firstChildState : 1;
-        unsigned lastChildState : 1;
 
         unsigned affectedByFocus : 1;
         unsigned affectedByHover : 1;
         unsigned affectedByActive : 1;
         unsigned affectedByDrag : 1;
 
         unsigned isLink : 1;
         // If you add more style bits here, you will also need to update RenderStyle::copyNonInheritedFrom()
         // 62 bits
     } noninherited_flags;
@@ skipping 32 matching lines @@
         noninherited_flags.tableLayout = initialTableLayout();
         noninherited_flags.unicodeBidi = initialUnicodeBidi();
         noninherited_flags.pageBreakBefore = initialPageBreak();
         noninherited_flags.pageBreakAfter = initialPageBreak();
         noninherited_flags.pageBreakInside = initialPageBreak();
         noninherited_flags.styleType = NOPSEUDO;
         noninherited_flags.pseudoBits = 0;
         noninherited_flags.explicitInheritance = false;
         noninherited_flags.unique = false;
         noninherited_flags.emptyState = false;
-        noninherited_flags.firstChildState = false;
-        noninherited_flags.lastChildState = false;
         noninherited_flags.hasViewportUnits = false;
         noninherited_flags.affectedByFocus = false;
         noninherited_flags.affectedByHover = false;
         noninherited_flags.affectedByActive = false;
         noninherited_flags.affectedByDrag = false;
         noninherited_flags.isLink = false;
     }
 
 private:
     ALWAYS_INLINE RenderStyle();
@@ skipping 1159 matching lines @@
     }
 
     // A unique style is one that has matches something that makes it impossible to share.
     bool unique() const { return noninherited_flags.unique; }
     void setUnique() { noninherited_flags.unique = true; }
 
     bool isSharable() const;
 
     bool emptyState() const { return noninherited_flags.emptyState; }
     void setEmptyState(bool b) { setUnique(); noninherited_flags.emptyState = b; }
-    bool firstChildState() const { return noninherited_flags.firstChildState; }
-    void setFirstChildState() { setUnique(); noninherited_flags.firstChildState = true; }
-    bool lastChildState() const { return noninherited_flags.lastChildState; }
-    void setLastChildState() { setUnique(); noninherited_flags.lastChildState = true; }
 
     StyleColor visitedDependentDecorationStyleColor() const;
     Color visitedDependentDecorationColor() const;
     Color visitedDependentColor(int colorProperty) const;
 
     void setHasExplicitlyInheritedProperties() { noninherited_flags.explicitInheritance = true; }
     bool hasExplicitlyInheritedProperties() const { return noninherited_flags.explicitInheritance; }
 
     bool hasBoxDecorations() const { return hasBorder() || hasBorderRadius() || hasOutline() || hasAppearance() || boxShadow() || hasFilter(); }
 
@@ skipping 382 matching lines @@
 inline bool RenderStyle::hasPseudoElementStyle() const
 {
     return noninherited_flags.pseudoBits & PSEUDO_ELEMENT_MASK;
 }
 
 float calcBorderRadiiConstraintScaleFor(const FloatRect&, const FloatRoundedRect::Radii&);
 
 } // namespace blink
 
 #endif // RenderStyle_h