Don't add rule feature data for rules which may never match.

third_party/WebKit/Source/core/css/CSSSelector.h

 /*
  * Copyright (C) 1999-2003 Lars Knoll (knoll@kde.org)
  *               1999 Waldo Bastian (bastian@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2008, 2009, 2010, 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 235 matching lines @@
     void setValue(const AtomicString&, bool matchLowerCase);
     void setAttribute(const QualifiedName&, AttributeMatchType);
     void setArgument(const AtomicString&);
     void setSelectorList(PassOwnPtr<CSSSelectorList>);
 
     void setNth(int a, int b);
     bool matchNth(int count) const;
 
     bool isAdjacentSelector() const { return m_relation == DirectAdjacent || m_relation == IndirectAdjacent; }
     bool isShadowSelector() const { return m_relation == ShadowPseudo || m_relation == ShadowDeep; }
-    bool isSiblingPseudo() const;
     bool isAttributeSelector() const { return m_match >= FirstAttributeSelectorMatch; }
     bool isHostPseudoClass() const { return m_pseudoType == PseudoHost || m_pseudoType == PseudoHostContext; }
     bool isInsertionPointCrossing() const { return m_pseudoType == PseudoHostContext || m_pseudoType == PseudoContent || m_pseudoType == PseudoSlotted; }
 
     Relation relation() const { return static_cast<Relation>(m_relation); }
     void setRelation(Relation relation)
     {
         m_relation = relation;
         ASSERT(static_cast<Relation>(m_relation) == relation); // using a bitfield.
     }
@@ skipping 91 matching lines @@
     return m_data.m_rareData->m_attribute;
 }
 
 inline CSSSelector::AttributeMatchType CSSSelector::attributeMatchType() const
 {
     ASSERT(isAttributeSelector());
     ASSERT(m_hasRareData);
     return m_data.m_rareData->m_bits.m_attributeMatchType;
 }
 
-inline bool CSSSelector::isSiblingPseudo() const
-{
-    PseudoType type = pseudoType();
-    return type == PseudoEmpty
-        || type == PseudoFirstChild
-        || type == PseudoFirstOfType
-        || type == PseudoLastChild
-        || type == PseudoLastOfType
-        || type == PseudoOnlyChild
-        || type == PseudoOnlyOfType
-        || type == PseudoNthChild
-        || type == PseudoNthOfType
-        || type == PseudoNthLastChild
-        || type == PseudoNthLastOfType;
-}
-
 inline bool CSSSelector::isASCIILower(const AtomicString& value)
 {
     for (size_t i = 0; i < value.length(); ++i) {
         if (isASCIIUpper(value[i]))
             return false;
     }
     return true;
 }
 
 inline void CSSSelector::setValue(const AtomicString& value, bool matchLowerCase = false)
@@ skipping 97 matching lines @@
     if (m_hasRareData)
         return m_data.m_rareData->m_serializingValue;
     // AtomicString is really just a StringImpl* so the cast below is safe.
     // FIXME: Perhaps call sites could be changed to accept StringImpl?
     return *reinterpret_cast<const AtomicString*>(&m_data.m_value);
 }
 
 } // namespace blink
 
 #endif // CSSSelector_h