Update HTML canvas classes to use OVERRIDE / FINAL when needed

Source/core/html/canvas/WebGLContextEvent.h

Index: Source/core/html/canvas/WebGLContextEvent.h
diff --git a/Source/core/html/canvas/WebGLContextEvent.h b/Source/core/html/canvas/WebGLContextEvent.h
index 18f4a4812f94613ee0b3027ee54c2034f1fae966..acba861b8ae96f9774c0fae36f29ae2c92d6448c 100644
--- a/Source/core/html/canvas/WebGLContextEvent.h
+++ b/Source/core/html/canvas/WebGLContextEvent.h
@@ -36,7 +36,7 @@ struct WebGLContextEventInit : public EventInit {
     String statusMessage;
 };
 
-class WebGLContextEvent : public Event {
+class WebGLContextEvent FINAL : public Event {
 public:
     static PassRefPtr<WebGLContextEvent> create()
     {
@@ -54,7 +54,7 @@ public:
 
     const String& statusMessage() const { return m_statusMessage; }
 
-    virtual const AtomicString& interfaceName() const;
+    virtual const AtomicString& interfaceName() const OVERRIDE;
 
 private:
     WebGLContextEvent();