IndexedDB: Replace 0 with nullptr where appropriate

Source/modules/indexeddb/DOMWindowIndexedDatabase.cpp

 /*
  * Copyright (C) 2011, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 66 matching lines @@
 
 IDBFactory* DOMWindowIndexedDatabase::indexedDB(DOMWindow& window)
 {
     return from(toLocalDOMWindow(window)).indexedDB();
 }
 
 IDBFactory* DOMWindowIndexedDatabase::indexedDB()
 {
     Document* document = m_window.document();
     if (!document)
-        return 0;
+        return nullptr;
 
     Page* page = document->page();
     if (!page)
-        return 0;
+        return nullptr;
 
     if (!m_window.isCurrentlyDisplayedInFrame())
-        return 0;
+        return nullptr;
 
     if (!m_idbFactory)
         m_idbFactory = IDBFactory::create(IndexedDBClient::create());
     return m_idbFactory.get();
 }
 
 } // namespace blink