Oilpan: remove redundant WILL_BE_EAGERLY_TRACED() declarations.

Source/core/css/StyleRule.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * (C) 2002-2003 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2002, 2006, 2008, 2012, 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 78 matching lines @@
     ~StyleRuleBase() { }
 
 private:
     void destroy();
 
     PassRefPtrWillBeRawPtr<CSSRule> createCSSOMWrapper(CSSStyleSheet* parentSheet, CSSRule* parentRule) const;
 
     unsigned m_type : 5;
 };
 
-WILL_BE_EAGERLY_TRACED(StyleRuleBase);
-
 class StyleRule : public StyleRuleBase {
     WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED;
 public:
     static PassRefPtrWillBeRawPtr<StyleRule> create() { return adoptRefWillBeNoop(new StyleRule()); }
 
     ~StyleRule();
 
     const CSSSelectorList& selectorList() const { return m_selectorList; }
     const StylePropertySet& properties() const { return *m_properties; }
     MutableStylePropertySet& mutableProperties();
@@ skipping 176 matching lines @@
 DEFINE_STYLE_RULE_TYPE_CASTS(FontFace);
 DEFINE_STYLE_RULE_TYPE_CASTS(Page);
 DEFINE_STYLE_RULE_TYPE_CASTS(Media);
 DEFINE_STYLE_RULE_TYPE_CASTS(Supports);
 DEFINE_STYLE_RULE_TYPE_CASTS(Viewport);
 DEFINE_STYLE_RULE_TYPE_CASTS(Filter);
 
 } // namespace blink
 
 #endif // StyleRule_h