Fix virtual/override/final usage in Source/core/{fetch,loader,streams,xmlhttprequest}/.

Source/core/xmlhttprequest/XMLHttpRequestUpload.h

 /*
  * Copyright (C) 2008 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:
  * 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 36 matching lines @@
         return adoptPtrWillBeNoop(new XMLHttpRequestUpload(xmlHttpRequest));
     }
 
 #if !ENABLE(OILPAN)
     void ref() { m_xmlHttpRequest->ref(); }
     void deref() { m_xmlHttpRequest->deref(); }
 #endif
 
     XMLHttpRequest* xmlHttpRequest() const { return m_xmlHttpRequest; }
 
-    virtual const AtomicString& interfaceName() const override;
-    virtual ExecutionContext* executionContext() const override;
+    const AtomicString& interfaceName() const override;
+    ExecutionContext* executionContext() const override;
 
     void dispatchEventAndLoadEnd(const AtomicString&, bool, unsigned long long, unsigned long long);
     void dispatchProgressEvent(unsigned long long, unsigned long long);
 
     void handleRequestError(const AtomicString&);
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit XMLHttpRequestUpload(XMLHttpRequest*);
 
 #if !ENABLE(OILPAN)
-    virtual void refEventTarget() override { ref(); }
-    virtual void derefEventTarget() override { deref(); }
+    void refEventTarget() override { ref(); }
+    void derefEventTarget() override { deref(); }
 #endif
 
     RawPtrWillBeMember<XMLHttpRequest> m_xmlHttpRequest;
 
     // Last progress event values; used when issuing the
     // required 'progress' event on a request error or abort.
     unsigned long long m_lastBytesSent;
     unsigned long long m_lastTotalBytesToBeSent;
 };
 
 } // namespace blink
 
 #endif // XMLHttpRequestUpload_h