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

Source/core/dom/ContainerNode.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011, 2013 Apple 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 32 matching lines @@
     ChildrenOrSiblingsAffectedByFocus = 1 << 0,
     ChildrenOrSiblingsAffectedByHover = 1 << 1,
     ChildrenOrSiblingsAffectedByActive = 1 << 2,
     ChildrenOrSiblingsAffectedByDrag = 1 << 3,
     ChildrenAffectedByFirstChildRules = 1 << 4,
     ChildrenAffectedByLastChildRules = 1 << 5,
     ChildrenAffectedByDirectAdjacentRules = 1 << 6,
     ChildrenAffectedByIndirectAdjacentRules = 1 << 7,
     ChildrenAffectedByForwardPositionalRules = 1 << 8,
     ChildrenAffectedByBackwardPositionalRules = 1 << 9,
+    AffectedByFirstChildRules = 1 << 10,
+    AffectedByLastChildRules = 1 << 11,
 
-    NumberOfDynamicRestyleFlags = 10,
+    NumberOfDynamicRestyleFlags = 12,
 };
 
 enum SubtreeModificationAction {
     DispatchSubtreeModifiedEvent,
     OmitSubtreeModifiedEvent
 };
 
 // This constant controls how much buffer is initially allocated
 // for a Node Vector that is used to store child Nodes of a given Node.
 // FIXME: Optimize the value.
@@ skipping 75 matching lines @@
 
     bool childrenAffectedByIndirectAdjacentRules() const { return hasRestyleFlag(ChildrenAffectedByIndirectAdjacentRules); }
     void setChildrenAffectedByIndirectAdjacentRules() { setRestyleFlag(ChildrenAffectedByIndirectAdjacentRules); }
 
     bool childrenAffectedByForwardPositionalRules() const { return hasRestyleFlag(ChildrenAffectedByForwardPositionalRules); }
     void setChildrenAffectedByForwardPositionalRules() { setRestyleFlag(ChildrenAffectedByForwardPositionalRules); }
 
     bool childrenAffectedByBackwardPositionalRules() const { return hasRestyleFlag(ChildrenAffectedByBackwardPositionalRules); }
     void setChildrenAffectedByBackwardPositionalRules() { setRestyleFlag(ChildrenAffectedByBackwardPositionalRules); }
 
+    bool affectedByFirstChildRules() const { return hasRestyleFlag(AffectedByFirstChildRules); }
+    void setAffectedByFirstChildRules() { setRestyleFlag(AffectedByFirstChildRules); }
+
+    bool affectedByLastChildRules() const { return hasRestyleFlag(AffectedByLastChildRules); }
+    void setAffectedByLastChildRules() { setRestyleFlag(AffectedByLastChildRules); }
+
     // FIXME: These methods should all be renamed to something better than "check",
     // since it's not clear that they alter the style bits of siblings and children.
     void checkForChildrenAdjacentRuleChanges();
     enum SiblingCheckType { FinishedParsingChildren, SiblingElementInserted, SiblingElementRemoved };
     void checkForSiblingStyleChanges(SiblingCheckType, Node* nodeBeforeChange, Node* nodeAfterChange);
     void recalcChildStyle(StyleRecalcChange);
 
     bool childrenSupportStyleSharing() const { return !hasRestyleFlags(); }
 
     // -----------------------------------------------------------------------------
@@ skipping 186 matching lines @@
 inline void getChildNodes(ContainerNode& node, NodeVector& nodes)
 {
     ASSERT(!nodes.size());
     for (Node* child = node.firstChild(); child; child = child->nextSibling())
         nodes.append(child);
 }
 
 } // namespace blink
 
 #endif // ContainerNode_h