Update Event classes to use OVERRIDE / FINAL when needed

Source/core/events/CustomEvent.h

Index: Source/core/events/CustomEvent.h
diff --git a/Source/core/events/CustomEvent.h b/Source/core/events/CustomEvent.h
index 9be0e119aa704c18c0bf355afb4cd55a8185c882..8b855d7d22fb9f546db97fa7369791cb15511827 100644
--- a/Source/core/events/CustomEvent.h
+++ b/Source/core/events/CustomEvent.h
@@ -34,7 +34,7 @@ class SerializedScriptValue;
 
 typedef EventInit CustomEventInit;
 
-class CustomEvent : public Event {
+class CustomEvent FINAL : public Event {
 public:
     virtual ~CustomEvent();
 
@@ -50,7 +50,7 @@ public:
 
     void initCustomEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtr<SerializedScriptValue>);
 
-    virtual const AtomicString& interfaceName() const;
+    virtual const AtomicString& interfaceName() const OVERRIDE;
 
     SerializedScriptValue* serializedDetail() { return m_serializedDetail.get(); }