Fix virtual/override/final usage in the rest of Source/core/.

Source/core/events/CompositionEvent.h

Index: Source/core/events/CompositionEvent.h
diff --git a/Source/core/events/CompositionEvent.h b/Source/core/events/CompositionEvent.h
index aaa8aba4fdf151ff275d8372027d6a1af65696af..8acd3f6e7fbb8e98f10ed1dd59c243dd3fec4c1c 100644
--- a/Source/core/events/CompositionEvent.h
+++ b/Source/core/events/CompositionEvent.h
@@ -50,13 +50,13 @@ public:
         return adoptRefWillBeNoop(new CompositionEvent(type, initializer));
     }
 
-    virtual ~CompositionEvent();
+    ~CompositionEvent() override;
 
     void initCompositionEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtrWillBeRawPtr<AbstractView>, const String& data);
 
     String data() const { return m_data; }
 
-    virtual const AtomicString& interfaceName() const override;
+    const AtomicString& interfaceName() const override;
 
     DECLARE_VIRTUAL_TRACE();