Do not zero-initialize RawPtr.

Source/core/css/CSSPrimitiveValue.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 1123 matching lines @@
     }
 
     ASSERT(!cssTextCache().contains(this));
     cssTextCache().set(this, text);
     m_hasCachedCSSText = true;
     return text;
 }
 
 PassRefPtrWillBeRawPtr<CSSPrimitiveValue> CSSPrimitiveValue::cloneForCSSOM() const
 {
-    RefPtrWillBeRawPtr<CSSPrimitiveValue> result;
+    RefPtrWillBeRawPtr<CSSPrimitiveValue> result = nullptr;
 
     switch (m_primitiveUnitType) {
     case CSS_STRING:
     case CSS_URI:
     case CSS_ATTR:
     case CSS_COUNTER_NAME:
         result = CSSPrimitiveValue::create(m_value.string, static_cast<UnitTypes>(m_primitiveUnitType));
         break;
     case CSS_COUNTER:
         result = CSSPrimitiveValue::create(m_value.counter->cloneForCSSOM());
@@ skipping 160 matching lines @@
     case CSS_SHAPE:
         visitor->trace(m_value.shape);
         break;
     default:
         break;
     }
     CSSValue::traceAfterDispatch(visitor);
 }
 
 } // namespace WebCore