Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/indexeddb/IDBTransaction.cpp

Index: Source/modules/indexeddb/IDBTransaction.cpp
diff --git a/Source/modules/indexeddb/IDBTransaction.cpp b/Source/modules/indexeddb/IDBTransaction.cpp
index e3e275ae74079bf2ecd0b2474b62d66e8608c12a..1384874afe8533fb06d519a058d345e58091f8a0 100644
--- a/Source/modules/indexeddb/IDBTransaction.cpp
+++ b/Source/modules/indexeddb/IDBTransaction.cpp
@@ -128,7 +128,7 @@ PassRefPtr<IDBObjectStore> IDBTransaction::objectStore(const String& name, Excep
 {
     if (m_state == Finished) {
         exceptionState.throwDOMException(InvalidStateError, IDBDatabase::transactionFinishedErrorMessage);
-        return 0;
+        return nullptr;
     }
 
     IDBObjectStoreMap::iterator it = m_objectStoreMap.find(name);
@@ -137,14 +137,14 @@ PassRefPtr<IDBObjectStore> IDBTransaction::objectStore(const String& name, Excep
 
     if (!isVersionChange() && !m_objectStoreNames.contains(name)) {
         exceptionState.throwDOMException(NotFoundError, IDBDatabase::noSuchObjectStoreErrorMessage);
-        return 0;
+        return nullptr;
     }
 
     int64_t objectStoreId = m_database->findObjectStoreId(name);
     if (objectStoreId == IDBObjectStoreMetadata::InvalidId) {
         ASSERT(isVersionChange());
         exceptionState.throwDOMException(NotFoundError, IDBDatabase::noSuchObjectStoreErrorMessage);
-        return 0;
+        return nullptr;
     }
 
     const IDBDatabaseMetadata& metadata = m_database->metadata();