Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/svg/SVGFEDropShadowElement.cpp

 /*
  * Copyright (C) Research In Motion Limited 2011. 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 105 matching lines @@
         return;
     }
 
     ASSERT_NOT_REACHED();
 }
 
 PassRefPtr<FilterEffect> SVGFEDropShadowElement::build(SVGFilterBuilder* filterBuilder, Filter* filter)
 {
     RenderObject* renderer = this->renderer();
     if (!renderer)
-        return 0;
+        return nullptr;
 
     if (stdDeviationX()->currentValue()->value() < 0 || stdDeviationY()->currentValue()->value() < 0)
-        return 0;
+        return nullptr;
 
     ASSERT(renderer->style());
     const SVGRenderStyle* svgStyle = renderer->style()->svgStyle();
 
     Color color = svgStyle->floodColor();
     float opacity = svgStyle->floodOpacity();
 
     FilterEffect* input1 = filterBuilder->getEffectById(AtomicString(m_in1->currentValue()->value()));
     if (!input1)
-        return 0;
+        return nullptr;
 
     RefPtr<FilterEffect> effect = FEDropShadow::create(filter, stdDeviationX()->currentValue()->value(), stdDeviationY()->currentValue()->value(), m_dx->currentValue()->value(), m_dy->currentValue()->value(), color, opacity);
     effect->inputEffects().append(input1);
     return effect.release();
 }
 
 }