Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/css/CSSFontFace.cpp

Index: Source/core/css/CSSFontFace.cpp
diff --git a/Source/core/css/CSSFontFace.cpp b/Source/core/css/CSSFontFace.cpp
index 46903927bba9e19fe1e6d0e040ef3bbcb5935ee6..0c2ebc31f383d130ece6fecc82a60f43a4891424 100644
--- a/Source/core/css/CSSFontFace.cpp
+++ b/Source/core/css/CSSFontFace.cpp
@@ -87,7 +87,7 @@ void CSSFontFace::fontLoaded(CSSFontFaceSource* source)
 PassRefPtr<SimpleFontData> CSSFontFace::getFontData(const FontDescription& fontDescription)
 {
     if (!isValid())
-        return 0;
+        return nullptr;
 
     while (!m_sources.isEmpty()) {
         OwnPtr<CSSFontFaceSource>& source = m_sources.first();
@@ -105,7 +105,7 @@ PassRefPtr<SimpleFontData> CSSFontFace::getFontData(const FontDescription& fontD
         setLoadStatus(FontFace::Loading);
     if (loadStatus() == FontFace::Loading)
         setLoadStatus(FontFace::Error);
-    return 0;
+    return nullptr;
 }
 
 void CSSFontFace::willUseFontData(const FontDescription& fontDescription)