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

Source/core/fetch/DocumentResource.h

 /*
     Copyright (C) 2010 Rob Buis <rwlbuis@gmail.com>
     Copyright (C) 2011 Cosmin Truta <ctruta@gmail.com>
     Copyright (C) 2012 University of Szeged
     Copyright (C) 2012 Renata Hodovan <reni@webkit.org>
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
@@ skipping 21 matching lines @@
 
 class Document;
 class FetchRequest;
 class ResourceFetcher;
 
 class DocumentResource final : public Resource {
 public:
     typedef ResourceClient ClientType;
 
     static ResourcePtr<DocumentResource> fetchSVGDocument(FetchRequest&, ResourceFetcher*);
-    virtual ~DocumentResource();
+    ~DocumentResource() override;
     DECLARE_VIRTUAL_TRACE();
 
     Document* document() const { return m_document.get(); }
 
-    virtual void setEncoding(const String&) override;
-    virtual String encoding() const override;
-    virtual void checkNotify() override;
+    void setEncoding(const String&) override;
+    String encoding() const override;
+    void checkNotify() override;
 
 private:
     class SVGDocumentResourceFactory : public ResourceFactory {
     public:
         SVGDocumentResourceFactory()
             : ResourceFactory(Resource::SVGDocument) { }
 
         Resource* create(const ResourceRequest& request, const String& charset) const override
         {
             return new DocumentResource(request, Resource::SVGDocument);
         }
     };
     DocumentResource(const ResourceRequest&, Type);
 
     PassRefPtrWillBeRawPtr<Document> createDocument(const KURL&);
 
     RefPtrWillBeMember<Document> m_document;
     OwnPtr<TextResourceDecoder> m_decoder;
 };
 
 DEFINE_TYPE_CASTS(DocumentResource, Resource, resource, resource->type() == Resource::SVGDocument, resource.type() == Resource::SVGDocument); \
 inline DocumentResource* toDocumentResource(const ResourcePtr<Resource>& ptr) { return toDocumentResource(ptr.get()); }
 
 class DocumentResourceClient : public ResourceClient {
 public:
-    virtual ~DocumentResourceClient() { }
+    ~DocumentResourceClient() override {}
     static ResourceClientType expectedType() { return DocumentType; }
-    virtual ResourceClientType resourceClientType() const override { return expectedType(); }
+    ResourceClientType resourceClientType() const override { return expectedType(); }
 };
 
 }
 
 #endif // DocumentResource_h