Update accessibility classes to use OVERRIDE / FINAL when needed

Source/core/accessibility/AXScrollbar.h

Index: Source/core/accessibility/AXScrollbar.h
diff --git a/Source/core/accessibility/AXScrollbar.h b/Source/core/accessibility/AXScrollbar.h
index 42eaca23470d57f8c596f83f7c1177f002085d6d..ec9bef0cf01b57222c63aff150f4804fe740c2dc 100644
--- a/Source/core/accessibility/AXScrollbar.h
+++ b/Source/core/accessibility/AXScrollbar.h
@@ -35,7 +35,7 @@ namespace WebCore {
 
 class Scrollbar;
 
-class AXScrollbar : public AXMockObject {
+class AXScrollbar FINAL : public AXMockObject {
 public:
     static PassRefPtr<AXScrollbar> create(Scrollbar*);
 
@@ -44,7 +44,7 @@ public:
 private:
     explicit AXScrollbar(Scrollbar*);
 
-    virtual void detachFromParent();
+    virtual void detachFromParent() OVERRIDE;
 
     virtual bool canSetValueAttribute() const OVERRIDE { return true; }