Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/svg/SVGFECompositeElement.cpp

Index: Source/core/svg/SVGFECompositeElement.cpp
diff --git a/Source/core/svg/SVGFECompositeElement.cpp b/Source/core/svg/SVGFECompositeElement.cpp
index 54326b60f430699b8e7f3449565f96e5665e78fc..43228411ddce10f53ab85ed8e243cd5a52e361c0 100644
--- a/Source/core/svg/SVGFECompositeElement.cpp
+++ b/Source/core/svg/SVGFECompositeElement.cpp
@@ -172,7 +172,7 @@ PassRefPtr<FilterEffect> SVGFECompositeElement::build(SVGFilterBuilder* filterBu
     FilterEffect* input2 = filterBuilder->getEffectById(AtomicString(m_in2->currentValue()->value()));
 
     if (!input1 || !input2)
-        return 0;
+        return nullptr;
 
     RefPtr<FilterEffect> effect = FEComposite::create(filter, m_svgOperator->currentValue()->enumValue(), m_k1->currentValue()->value(), m_k2->currentValue()->value(), m_k3->currentValue()->value(), m_k4->currentValue()->value());
     FilterEffectVector& inputEffects = effect->inputEffects();