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

Source/core/dom/custom/CustomElementUpgradeCandidateMap.h

Index: Source/core/dom/custom/CustomElementUpgradeCandidateMap.h
diff --git a/Source/core/dom/custom/CustomElementUpgradeCandidateMap.h b/Source/core/dom/custom/CustomElementUpgradeCandidateMap.h
index 8a6756907156c8beab65e9d5c0852ad86a1aac92..bdfcc4262c1b594e8bd4d44f601854c4c9221d76 100644
--- a/Source/core/dom/custom/CustomElementUpgradeCandidateMap.h
+++ b/Source/core/dom/custom/CustomElementUpgradeCandidateMap.h
@@ -44,7 +44,7 @@ class CustomElementUpgradeCandidateMap final : public CustomElementObserver {
     WTF_MAKE_NONCOPYABLE(CustomElementUpgradeCandidateMap);
 public:
     static PassOwnPtrWillBeRawPtr<CustomElementUpgradeCandidateMap> create();
-    virtual ~CustomElementUpgradeCandidateMap();
+    ~CustomElementUpgradeCandidateMap() override;
 
     // API for CustomElementRegistrationContext to save and take candidates
 
@@ -58,7 +58,7 @@ public:
 private:
     CustomElementUpgradeCandidateMap() { }
 
-    virtual void elementWasDestroyed(Element*) override;
+    void elementWasDestroyed(Element*) override;
 
     typedef WillBeHeapHashMap<RawPtrWillBeWeakMember<Element>, CustomElementDescriptor> UpgradeCandidateMap;
     UpgradeCandidateMap m_upgradeCandidates;