Prevent integer overflows in ANPlusB handling

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 266 matching lines @@
   void Show(int indent) const;
 #endif
 
   bool IsASCIILower(const AtomicString& value);
   void SetValue(const AtomicString&, bool match_lower_case);
   void SetAttribute(const QualifiedName&, AttributeMatchType);
   void SetArgument(const AtomicString&);
   void SetSelectorList(std::unique_ptr<CSSSelectorList>);
 
   void SetNth(int a, int b);
-  bool MatchNth(int count) const;
+  bool MatchNth(unsigned count) const;
 
   bool IsAdjacentSelector() const {
     return relation_ == kDirectAdjacent || relation_ == kIndirectAdjacent;
   }
   bool IsShadowSelector() const {
     return relation_ == kShadowPseudo || relation_ == kShadowDeep;
   }
   bool IsAttributeSelector() const {
     return match_ >= kFirstAttributeSelectorMatch;
   }
@@ skipping 73 matching lines @@
 
   // Hide.
   CSSSelector& operator=(const CSSSelector&);
 
   struct RareData : public RefCounted<RareData> {
     static PassRefPtr<RareData> Create(const AtomicString& value) {
       return AdoptRef(new RareData(value));
     }
     ~RareData();
 
-    bool MatchNth(int count);
+    bool MatchNth(unsigned count);
     int NthAValue() const { return bits_.nth_.a_; }
     int NthBValue() const { return bits_.nth_.b_; }
 
     AtomicString matching_value_;
     AtomicString serializing_value_;
     union {
       struct {
         int a_;  // Used for :nth-*
         int b_;  // Used for :nth-*
       } nth_;
@@ skipping 145 matching lines @@
 }
 
 inline bool CSSSelector::IsIdClassOrAttributeSelector() const {
   return IsAttributeSelector() || Match() == CSSSelector::kId ||
          Match() == CSSSelector::kClass;
 }
 
 }  // namespace blink
 
 #endif  // CSSSelector_h