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

Source/core/html/HTMLShadowElement.h

Index: Source/core/html/HTMLShadowElement.h
diff --git a/Source/core/html/HTMLShadowElement.h b/Source/core/html/HTMLShadowElement.h
index 9a953f09cd93a0a56dbff95b2da3f71962d8bc22..c760fc6610fad9a18449446f33c4b656054268e4 100644
--- a/Source/core/html/HTMLShadowElement.h
+++ b/Source/core/html/HTMLShadowElement.h
@@ -40,13 +40,13 @@ class HTMLShadowElement final : public InsertionPoint {
     DEFINE_WRAPPERTYPEINFO();
 public:
     DECLARE_NODE_FACTORY(HTMLShadowElement);
-    virtual ~HTMLShadowElement();
+    ~HTMLShadowElement() override;
 
     ShadowRoot* olderShadowRoot();
 
 private:
     explicit HTMLShadowElement(Document&);
-    virtual InsertionNotificationRequest insertedInto(ContainerNode* insertionPoint) override;
+    InsertionNotificationRequest insertedInto(ContainerNode* insertionPoint) override;
 };
 
 } // namespace blink