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

Source/core/loader/LinkLoader.h

Index: Source/core/loader/LinkLoader.h
diff --git a/Source/core/loader/LinkLoader.h b/Source/core/loader/LinkLoader.h
index 0cf7e290f0173bca06842fec046ead8bad296141..a23673bd86dd00f8b3fca81182dff5ed74c0f0a0 100644
--- a/Source/core/loader/LinkLoader.h
+++ b/Source/core/loader/LinkLoader.h
@@ -52,16 +52,16 @@ class CORE_EXPORT LinkLoader final : public ResourceOwner<Resource, ResourceClie
     DISALLOW_ALLOCATION();
 public:
     explicit LinkLoader(LinkLoaderClient*);
-    virtual ~LinkLoader();
+    ~LinkLoader() override;
 
     // from ResourceClient
-    virtual void notifyFinished(Resource*) override;
+    void notifyFinished(Resource*) override;
 
     // from PrerenderClient
-    virtual void didStartPrerender() override;
-    virtual void didStopPrerender() override;
-    virtual void didSendLoadForPrerender() override;
-    virtual void didSendDOMContentLoadedForPrerender() override;
+    void didStartPrerender() override;
+    void didStopPrerender() override;
+    void didSendLoadForPrerender() override;
+    void didSendDOMContentLoadedForPrerender() override;
 
     void released();
     bool loadLink(const LinkRelAttribute&, const AtomicString& crossOriginMode, const String& type, const String& as, const KURL&, Document&);