Oilpan: Replace RefPtrs to Node and its subclasses in core/loader with Oilpan transition types.

Source/core/html/imports/HTMLImportLoader.cpp

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 74 matching lines @@
     // being added as a client later & now being notified. Fail early.
     if (resource->loadFailedOrCanceled() || response.httpStatusCode() >= 400) {
         setState(StateError);
         return;
     }
     setState(startWritingAndParsing(response));
 }
 
 void HTMLImportLoader::dataReceived(Resource*, const char* data, int length)
 {
-    RefPtr<DocumentWriter> protectingWriter(m_writer);
+    RefPtrWillBeRawPtr<DocumentWriter> protectingWriter(m_writer.get());
     m_writer->addData(data, length);
 }
 
 void HTMLImportLoader::notifyFinished(Resource* resource)
 {
     // The writer instance indicates that a part of the document can be already loaded.
     // We don't take such a case as an error because the partially-loaded document has been visible from script at this point.
     if (resource->loadFailedOrCanceled() && !m_writer) {
         setState(StateError);
         return;
@@ skipping 29 matching lines @@
 }
 
 void HTMLImportLoader::setState(State state)
 {
     if (m_state == state)
         return;
 
     m_state = state;
 
     if (m_state == StateParsed || m_state == StateError || m_state == StateWritten) {
-        if (RefPtr<DocumentWriter> writer = m_writer.release())
+        if (RefPtrWillBeRawPtr<DocumentWriter> writer = m_writer.release())
             writer->end();
     }
 
     // Since DocumentWriter::end() can let setState() reenter, we shouldn't refer to m_state here.
     if (state == StateLoaded || state == StateError)
         didFinishLoading();
 }
 
 void HTMLImportLoader::didFinishParsing()
 {
@@ skipping 59 matching lines @@
     return m_microtaskQueue;
 }
 
 void HTMLImportLoader::trace(Visitor* visitor)
 {
     visitor->trace(m_controller);
 #if ENABLE(OILPAN)
     visitor->trace(m_imports);
 #endif
     visitor->trace(m_document);
+    visitor->trace(m_writer);
     visitor->trace(m_microtaskQueue);
 }
 
 } // namespace WebCore