Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/SharedBuffer.cpp

Index: Source/platform/SharedBuffer.cpp
diff --git a/Source/platform/SharedBuffer.cpp b/Source/platform/SharedBuffer.cpp
index de19773a840dc51de693db5149ececf24b8b1c26..2aafd62d972131b0c44220eb7ab0c17dee06e2a6 100644
--- a/Source/platform/SharedBuffer.cpp
+++ b/Source/platform/SharedBuffer.cpp
@@ -431,7 +431,7 @@ PassRefPtr<ArrayBuffer> SharedBuffer::getAsArrayBuffer() const
     if (position != arrayBuffer->byteLength()) {
         ASSERT_NOT_REACHED();
         // Don't return the incomplete ArrayBuffer.
-        return 0;
+        return nullptr;
     }
 
     return arrayBuffer;
@@ -451,7 +451,7 @@ PassRefPtr<SkData> SharedBuffer::getAsSkData() const
     if (position != bufferLength) {
         ASSERT_NOT_REACHED();
         // Don't return the incomplete SkData.
-        return 0;
+        return nullptr;
     }
     return adoptRef(SkData::NewFromMalloc(buffer, bufferLength));
 }