Fix virtual/override/final usage in Source/web/.

Source/web/ExternalDateTimeChooser.h

Index: Source/web/ExternalDateTimeChooser.h
diff --git a/Source/web/ExternalDateTimeChooser.h b/Source/web/ExternalDateTimeChooser.h
index 35204be4021f80207e3f78857c16757aa7326d23..19ef587d5246b2a1ae2281d83d4a6d891d5db070 100644
--- a/Source/web/ExternalDateTimeChooser.h
+++ b/Source/web/ExternalDateTimeChooser.h
@@ -39,7 +39,7 @@ class WebViewClient;
 class ExternalDateTimeChooser final : public DateTimeChooser {
 public:
     static PassRefPtr<ExternalDateTimeChooser> create(ChromeClientImpl*, WebViewClient*, DateTimeChooserClient*, const DateTimeChooserParameters&);
-    virtual ~ExternalDateTimeChooser();
+    ~ExternalDateTimeChooser() override;
 
     // The following functions are for DateTimeChooserCompletion.
     void didChooseValue(const WebString&);
@@ -51,8 +51,8 @@ private:
     bool openDateTimeChooser(ChromeClientImpl*, WebViewClient*, const DateTimeChooserParameters&);
 
     // DateTimeChooser function:
-    virtual void endChooser() override;
-    virtual AXObject* rootAXObject() override;
+    void endChooser() override;
+    AXObject* rootAXObject() override;
 
     DateTimeChooserClient* m_client;
 };