Update DOM classes to use OVERRIDE / FINAL when needed

Source/core/dom/DatasetDOMStringMap.h

Index: Source/core/dom/DatasetDOMStringMap.h
diff --git a/Source/core/dom/DatasetDOMStringMap.h b/Source/core/dom/DatasetDOMStringMap.h
index 7b4177ee3ece5c6a0952c197d7f1ae79d6f4c5d9..9d2220f237ff6a7066520bb3e7aee371379b2c7b 100644
--- a/Source/core/dom/DatasetDOMStringMap.h
+++ b/Source/core/dom/DatasetDOMStringMap.h
@@ -34,23 +34,23 @@ namespace WebCore {
 class Element;
 class ExceptionState;
 
-class DatasetDOMStringMap : public DOMStringMap {
+class DatasetDOMStringMap FINAL : public DOMStringMap {
 public:
     static PassOwnPtr<DatasetDOMStringMap> create(Element* element)
     {
         return adoptPtr(new DatasetDOMStringMap(element));
     }
 
-    virtual void ref();
-    virtual void deref();
+    virtual void ref() OVERRIDE;
+    virtual void deref() OVERRIDE;
 
-    virtual void getNames(Vector<String>&);
-    virtual String item(const String& name);
-    virtual bool contains(const String& name);
-    virtual void setItem(const String& name, const String& value, ExceptionState&);
-    virtual bool deleteItem(const String& name);
+    virtual void getNames(Vector<String>&) OVERRIDE;
+    virtual String item(const String& name) OVERRIDE;
+    virtual bool contains(const String& name) OVERRIDE;
+    virtual void setItem(const String& name, const String& value, ExceptionState&) OVERRIDE;
+    virtual bool deleteItem(const String& name) OVERRIDE;
 
-    virtual Element* element() { return m_element; }
+    virtual Element* element() OVERRIDE { return m_element; }
 
 private:
     explicit DatasetDOMStringMap(Element* element)