[WIP] do something :-)

Source/core/css/StyleRule.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * (C) 2002-2003 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2002, 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.
  *
@@ skipping 15 matching lines @@
 #include "core/css/CSSImportRule.h"
 #include "core/css/CSSKeyframesRule.h"
 #include "core/css/CSSMediaRule.h"
 #include "core/css/CSSPageRule.h"
 #include "core/css/CSSStyleRule.h"
 #include "core/css/CSSSupportsRule.h"
 #include "core/css/CSSViewportRule.h"
 #include "core/css/StyleRuleImport.h"
 #include "core/css/StyleRuleKeyframe.h"
 #include "core/css/StyleRuleNamespace.h"
+#include "wtf/SizeAssertions.h"
 
 namespace blink {
 
-struct SameSizeAsStyleRuleBase : public RefCountedWillBeGarbageCollectedFinalized<SameSizeAsStyleRuleBase> {
-    unsigned bitfields;
-};
-
-static_assert(sizeof(StyleRuleBase) <= sizeof(SameSizeAsStyleRuleBase), "StyleRuleBase should stay small");
+ASSERT_SIZE(StyleRuleBase, 8, 8);
 
 PassRefPtrWillBeRawPtr<CSSRule> StyleRuleBase::createCSSOMWrapper(CSSStyleSheet* parentSheet) const
 {
     return createCSSOMWrapper(parentSheet, 0);
 }
 
 PassRefPtrWillBeRawPtr<CSSRule> StyleRuleBase::createCSSOMWrapper(CSSRule* parentRule) const
 {
     return createCSSOMWrapper(0, parentRule);
 }
@@ skipping 371 matching lines @@
     return *toMutableStylePropertySet(m_properties);
 }
 
 DEFINE_TRACE_AFTER_DISPATCH(StyleRuleViewport)
 {
     visitor->trace(m_properties);
     StyleRuleBase::traceAfterDispatch(visitor);
 }
 
 } // namespace blink