Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/workers/WorkerThread.cpp

Index: Source/core/workers/WorkerThread.cpp
diff --git a/Source/core/workers/WorkerThread.cpp b/Source/core/workers/WorkerThread.cpp
index 177662229b008c6e4e7b3314444d8cea2b7671dd..c3d8044a2038ea2438d92ab5c3cc103598875ade 100644
--- a/Source/core/workers/WorkerThread.cpp
+++ b/Source/core/workers/WorkerThread.cpp
@@ -140,7 +140,7 @@ void WorkerThread::workerThread()
 
     // The below assignment will destroy the context, which will in turn notify messaging proxy.
     // We cannot let any objects survive past thread exit, because no other thread will run GC or otherwise destroy them.
-    m_workerGlobalScope = 0;
+    m_workerGlobalScope = nullptr;
 
     // Cleanup thread heap which causes all objects to be finalized.
     // After this call thread heap must be empty.