Use toDocument instead of static_cast<Document*>.

Source/core/workers/SharedWorker.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 Apple 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 36 matching lines @@
 
 inline SharedWorker::SharedWorker(ScriptExecutionContext* context)
     : AbstractWorker(context)
 {
     ScriptWrappable::init(this);
 }
 
 PassRefPtr<SharedWorker> SharedWorker::create(ScriptExecutionContext* context, const String& url, const String& name, ExceptionCode& ec)
 {
     ASSERT(isMainThread());
-    UseCounter::count(static_cast<Document*>(context)->domWindow(), UseCounter::SharedWorkerStart);
+    UseCounter::count(toDocument(context)->domWindow(), UseCounter::SharedWorkerStart);
 
     RefPtr<SharedWorker> worker = adoptRef(new SharedWorker(context));
 
     RefPtr<MessageChannel> channel = MessageChannel::create(context);
     worker->m_port = channel->port1();
     OwnPtr<MessagePortChannel> remotePort = channel->port2()->disentangle();
     ASSERT(remotePort);
 
     worker->suspendIfNeeded();
 
     KURL scriptURL = worker->resolveURL(url, ec);
     if (scriptURL.isEmpty())
         return 0;
 
     // We don't currently support nested workers, so workers can only be created from documents.
     ASSERT_WITH_SECURITY_IMPLICATION(context->isDocument());
-    Document* document = static_cast<Document*>(context);
+    Document* document = toDocument(context);
     if (!document->securityOrigin()->canAccessSharedWorkers(document->topOrigin())) {
         ec = SECURITY_ERR;
         return 0;
     }
 
     SharedWorkerRepository::connect(worker.get(), remotePort.release(), scriptURL, name, ec);
 
     return worker.release();
 }
 
 SharedWorker::~SharedWorker()
 {
 }
 
 const AtomicString& SharedWorker::interfaceName() const
 {
     return eventNames().interfaceForSharedWorker;
 }
 
 } // namespace WebCore