Fix virtual/override/final usage in Source/core/html/.

Source/core/html/shadow/ClearButtonElement.h

Index: Source/core/html/shadow/ClearButtonElement.h
diff --git a/Source/core/html/shadow/ClearButtonElement.h b/Source/core/html/shadow/ClearButtonElement.h
index 6bbb82847875a06e0ba6c0266bfb0476bb79a089..6fa6dbb626e2ec34ae9f04a449608823fd29acdd 100644
--- a/Source/core/html/shadow/ClearButtonElement.h
+++ b/Source/core/html/shadow/ClearButtonElement.h
@@ -48,10 +48,10 @@ public:
 
 private:
     ClearButtonElement(Document&, ClearButtonOwner&);
-    virtual void detach(const AttachContext& = AttachContext()) override;
-    virtual bool isMouseFocusable() const override { return false; }
-    virtual void defaultEventHandler(Event*) override;
-    virtual bool isClearButtonElement() const override;
+    void detach(const AttachContext& = AttachContext()) override;
+    bool isMouseFocusable() const override { return false; }
+    void defaultEventHandler(Event*) override;
+    bool isClearButtonElement() const override;
 
     RawPtrWillBeMember<ClearButtonOwner> m_clearButtonOwner;
 };