Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/svg/SVGFEMorphologyElement.cpp

 /*
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  *
  * 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 131 matching lines @@
     ASSERT_NOT_REACHED();
 }
 
 PassRefPtr<FilterEffect> SVGFEMorphologyElement::build(SVGFilterBuilder* filterBuilder, Filter* filter)
 {
     FilterEffect* input1 = filterBuilder->getEffectById(AtomicString(m_in1->currentValue()->value()));
     float xRadius = radiusX()->currentValue()->value();
     float yRadius = radiusY()->currentValue()->value();
 
     if (!input1)
-        return 0;
+        return nullptr;
 
     if (xRadius < 0 || yRadius < 0)
-        return 0;
+        return nullptr;
 
     RefPtr<FilterEffect> effect = FEMorphology::create(filter, m_svgOperator->currentValue()->enumValue(), xRadius, yRadius);
     effect->inputEffects().append(input1);
     return effect.release();
 }
 
 } // namespace WebCore