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

Source/core/html/LabelableElement.h

Index: Source/core/html/LabelableElement.h
diff --git a/Source/core/html/LabelableElement.h b/Source/core/html/LabelableElement.h
index 13fd0a4be9b0ddac65997bfe886f248b70367717..175d27792b170bac859c7904785b4538d7680b35 100644
--- a/Source/core/html/LabelableElement.h
+++ b/Source/core/html/LabelableElement.h
@@ -42,7 +42,7 @@ class LabelsNodeList;
 // specification, and provides the implementation of the "labels" attribute.
 class CORE_EXPORT LabelableElement : public HTMLElement {
 public:
-    virtual ~LabelableElement();
+    ~LabelableElement() override;
     PassRefPtrWillBeRawPtr<LabelsNodeList> labels();
     virtual bool supportLabels() const { return false; }
 
@@ -52,7 +52,7 @@ protected:
     LabelableElement(const QualifiedName& tagName, Document&);
 
 private:
-    virtual bool isLabelable() const override final { return true; }
+    bool isLabelable() const final { return true; }
 };
 
 inline bool isLabelableElement(const HTMLElement& element)