Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/graphics/filters/FELighting.cpp

Index: Source/platform/graphics/filters/FELighting.cpp
diff --git a/Source/platform/graphics/filters/FELighting.cpp b/Source/platform/graphics/filters/FELighting.cpp
index c3e1ba14f20957b0a40fb49ecf24460ea2a3fc80..4214ba9f4520448aaef9d6208b17cc1db0133189 100644
--- a/Source/platform/graphics/filters/FELighting.cpp
+++ b/Source/platform/graphics/filters/FELighting.cpp
@@ -423,7 +423,7 @@ PassRefPtr<SkImageFilter> FELighting::createImageFilter(SkiaImageFilterBuilder*
 {
     SkImageFilter::CropRect rect = getCropRect(builder ? builder->cropOffset() : FloatSize());
     Color lightColor = adaptColorToOperatingColorSpace(m_lightingColor);
-    RefPtr<SkImageFilter> input(builder ? builder->build(inputEffect(0), operatingColorSpace()) : 0);
+    RefPtr<SkImageFilter> input(builder ? builder->build(inputEffect(0), operatingColorSpace()) : nullptr);
     switch (m_lightSource->type()) {
     case LS_DISTANT: {
         DistantLightSource* distantLightSource = static_cast<DistantLightSource*>(m_lightSource.get());
@@ -458,7 +458,7 @@ PassRefPtr<SkImageFilter> FELighting::createImageFilter(SkiaImageFilterBuilder*
     }
     default:
         ASSERT_NOT_REACHED();
-        return 0;
+        return nullptr;
     }
 }