Oilpan: remove redundant WILL_BE_EAGERLY_TRACED() declarations.

Source/core/css/StylePropertySet.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2008, 2012 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 130 matching lines @@
         , m_arraySize(std::min(immutableArraySize, unsigned(MaxArraySize)))
     { }
 
     unsigned m_cssParserMode : 3;
     mutable unsigned m_isMutable : 1;
     unsigned m_arraySize : 28;
 
     friend class PropertySetCSSStyleDeclaration;
 };
 
-WILL_BE_EAGERLY_TRACED(StylePropertySet);
-
 class ImmutableStylePropertySet : public StylePropertySet {
 public:
     ~ImmutableStylePropertySet();
     static PassRefPtrWillBeRawPtr<ImmutableStylePropertySet> create(const CSSProperty* properties, unsigned count, CSSParserMode);
 
     unsigned propertyCount() const { return m_arraySize; }
 
     const RawPtrWillBeMember<CSSValue>* valueArray() const;
     const StylePropertyMetadata* metadataArray() const;
     int findPropertyIndex(CSSPropertyID) const;
@@ skipping 134 matching lines @@
 inline int StylePropertySet::findPropertyIndex(CSSPropertyID propertyID) const
 {
     if (m_isMutable)
         return toMutableStylePropertySet(this)->findPropertyIndex(propertyID);
     return toImmutableStylePropertySet(this)->findPropertyIndex(propertyID);
 }
 
 } // namespace blink
 
 #endif // StylePropertySet_h