Update Event classes to use OVERRIDE / FINAL when needed

Source/core/events/OverflowEvent.h

Index: Source/core/events/OverflowEvent.h
diff --git a/Source/core/events/OverflowEvent.h b/Source/core/events/OverflowEvent.h
index 96c220b219872ab311a98ce887ea26ed1c6c9447..fe759cf5a47704feac1cfaad17782619c84e6c72 100644
--- a/Source/core/events/OverflowEvent.h
+++ b/Source/core/events/OverflowEvent.h
@@ -38,7 +38,7 @@ struct OverflowEventInit : public EventInit {
     bool verticalOverflow;
 };
 
-class OverflowEvent : public Event {
+class OverflowEvent FINAL : public Event {
 public:
     enum orientType {
         HORIZONTAL = 0,
@@ -65,7 +65,7 @@ public:
     bool horizontalOverflow() const { return m_horizontalOverflow; }
     bool verticalOverflow() const { return m_verticalOverflow; }
 
-    virtual const AtomicString& interfaceName() const;
+    virtual const AtomicString& interfaceName() const OVERRIDE;
 
 private:
     OverflowEvent();