Fix serialization of content property to always quote

Source/core/css/CSSValueList.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 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 36 matching lines @@
     const CSSValue* item(size_t index) const { return m_values[index].get(); }
     CSSValue* itemWithBoundsCheck(size_t index) { return index < m_values.size() ? m_values[index].get() : 0; }
     const CSSValue* itemWithBoundsCheck(size_t index) const { return index < m_values.size() ? m_values[index].get() : 0; }
 
     void append(PassRefPtrWillBeRawPtr<CSSValue> value) { m_values.append(value); }
     void prepend(PassRefPtrWillBeRawPtr<CSSValue> value) { m_values.prepend(value); }
     bool removeAll(CSSValue*);
     bool hasValue(CSSValue*) const;
     PassRefPtrWillBeRawPtr<CSSValueList> copy();
 
-    String customCSSText(CSSTextFormattingFlags = QuoteCSSStringIfNeeded) const;
+    String customCSSText() const;
     bool equals(const CSSValueList&) const;
     bool equals(const CSSValue&) const;
 
     bool hasFailedOrCanceledSubresources() const;
 
     DECLARE_TRACE_AFTER_DISPATCH();
 
 protected:
     CSSValueList(ClassType, ValueListSeparator);
 
@@ skipping 17 matching lines @@
     void advance() { m_position++; ASSERT(m_position <= m_list->length());}
     size_t index() const { return m_position; }
 private:
     RawPtrWillBeMember<CSSValueList> m_list;
     size_t m_position;
 };
 
 } // namespace blink
 
 #endif // CSSValueList_h