Do not zero-initialize RawPtr.

Source/core/css/CSSValueList.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 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 57 matching lines @@
     for (size_t index = 0; index < m_values.size(); index++) {
         const RefPtrWillBeMember<CSSValue>& value = m_values.at(index);
         if (value && val && value->equals(*val))
             return true;
     }
     return false;
 }
 
 PassRefPtrWillBeRawPtr<CSSValueList> CSSValueList::copy()
 {
-    RefPtrWillBeRawPtr<CSSValueList> newList;
+    RefPtrWillBeRawPtr<CSSValueList> newList = nullptr;
     switch (m_valueListSeparator) {
     case SpaceSeparator:
         newList = createSpaceSeparated();
         break;
     case CommaSeparator:
         newList = createCommaSeparated();
         break;
     case SlashSeparator:
         newList = createSlashSeparated();
         break;
@@ skipping 73 matching lines @@
     return adoptRefWillBeRefCountedGarbageCollected(new CSSValueList(*this));
 }
 
 void CSSValueList::traceAfterDispatch(Visitor* visitor)
 {
     visitor->trace(m_values);
     CSSValue::traceAfterDispatch(visitor);
 }
 
 } // namespace WebCore