Add DataPersistent<> for copy-on-modify and use for StyleFilterData.

third_party/WebKit/Source/core/style/StyleRareNonInheritedData.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 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 22 matching lines @@
 
 class SameSizeStyleRareNonInheritedData : public RefCounted<StyleRareNonInheritedData> {
 public:
     float floats[3];
     int integers;
 
     LengthPoint lengthPoints[2];
     LineClampValue lineClamps;
     DraggableRegionMode draggableRegions;
 
-    void* dataRefs[10];
+    void* dataRefs[8];
+    DataPersistent<void*> dataPersistents[2];
     void* ownPtrs[4];
     Persistent<void*> persistentHandles[2];
     void* refPtrs[2];
 
     FillLayer fillLayers;
     NinePieceImage ninePieces;
     FloatSize floatSize;
     Length lengths;
 
     StyleColor styleColors[8];
@@ skipping 294 matching lines @@
 {
     return dataEquivalent(m_shapeOutside, o.m_shapeOutside);
 }
 
 bool StyleRareNonInheritedData::clipPathDataEquivalent(const StyleRareNonInheritedData& o) const
 {
     return dataEquivalent(m_clipPath, o.m_clipPath);
 }
 
 } // namespace blink