[WIP] do something :-)

Source/core/dom/ElementData.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 15 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/dom/ElementData.h"
 
 #include "core/css/StylePropertySet.h"
 #include "core/dom/QualifiedName.h"
+#include "wtf/SizeAssertions.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
-struct SameSizeAsElementData : public RefCountedWillBeGarbageCollectedFinalized<SameSizeAsElementData> {
-    unsigned bitfield;
-    void* pointers[3];
-};
-
-static_assert(sizeof(ElementData) == sizeof(SameSizeAsElementData), "ElementData should stay small");
+ASSERT_SIZE(ElementData, 20, 32);
 
 static size_t sizeForShareableElementDataWithAttributeCount(unsigned count)
 {
     return sizeof(ShareableElementData) + sizeof(Attribute) * count;
 }
 
 ElementData::ElementData()
     : m_isUnique(true)
     , m_arraySize(0)
     , m_presentationAttributeStyleIsDirty(false)
@@ skipping 155 matching lines @@
     return adoptRefWillBeNoop(new (slot) ShareableElementData(*this));
 }
 
 DEFINE_TRACE_AFTER_DISPATCH(UniqueElementData)
 {
     visitor->trace(m_presentationAttributeStyle);
     ElementData::traceAfterDispatch(visitor);
 }
 
 } // namespace blink