Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/websockets/MainThreadWebSocketChannel.cpp

Index: Source/modules/websockets/MainThreadWebSocketChannel.cpp
diff --git a/Source/modules/websockets/MainThreadWebSocketChannel.cpp b/Source/modules/websockets/MainThreadWebSocketChannel.cpp
index 9c9c7fc61363325018414491bcad7657b7ee8d9d..9c6fb379465f07e651108692b8b540bbc08e4f5e 100644
--- a/Source/modules/websockets/MainThreadWebSocketChannel.cpp
+++ b/Source/modules/websockets/MainThreadWebSocketChannel.cpp
@@ -291,7 +291,7 @@ void MainThreadWebSocketChannel::didCloseSocketStream(SocketStreamHandle* handle
         WebSocketChannelClient* client = m_client;
         m_client = 0;
         clearDocument();
-        m_handle = 0;
+        m_handle = nullptr;
         if (client)
             client->didClose(m_unhandledBufferedAmount, m_receivedClosingHandshake ? WebSocketChannelClient::ClosingHandshakeComplete : WebSocketChannelClient::ClosingHandshakeIncomplete, m_closeEventCode, m_closeEventReason);
     }