Consistently use on-heap collections for StyleRuleBase descendants.

Source/core/css/resolver/MatchResult.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google 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 52 matching lines @@
             unsigned whitelistType : 2;
         };
         // Used to make sure all memory is zero-initialized since we compute the hash over the bytes of this object.
         void* possiblyPaddedMember;
     };
 };
 
 struct MatchResult {
     MatchResult() : isCacheable(true) { }
     Vector<MatchedProperties, 64> matchedProperties;
-    Vector<StyleRule*, 64> matchedRules;
+    WillBeHeapVector<StyleRule*, 64> matchedRules;
     MatchRanges ranges;
     bool isCacheable;
 
     void addMatchedProperties(const StylePropertySet* properties, StyleRule* = 0, unsigned linkMatchType = SelectorChecker::MatchAll, PropertyWhitelistType = PropertyWhitelistNone);
 };
 
 inline bool operator==(const MatchRanges& a, const MatchRanges& b)
 {
     return a.firstUARule == b.firstUARule
         && a.lastUARule == b.lastUARule
@@ skipping 14 matching lines @@
 }
 
 inline bool operator!=(const MatchedProperties& a, const MatchedProperties& b)
 {
     return !(a == b);
 }
 
 } // namespace WebCore
 
 #endif // MatchResult_h