Fix virtual/override/final usage in the rest of Source/core/.

Source/core/timing/PerformanceRenderTiming.h

Index: Source/core/timing/PerformanceRenderTiming.h
diff --git a/Source/core/timing/PerformanceRenderTiming.h b/Source/core/timing/PerformanceRenderTiming.h
index 6aad0945831609b77a2203d0dc5ea503596e0eb0..87e115b15e4c569fdfb72e8d1bf88501d20f8d34 100644
--- a/Source/core/timing/PerformanceRenderTiming.h
+++ b/Source/core/timing/PerformanceRenderTiming.h
@@ -51,13 +51,13 @@ public:
 
     unsigned sourceFrame() const;
 
-    virtual bool isRender() override { return true; }
+    bool isRender() override { return true; }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     PerformanceRenderTiming(Document* requestingDocument, unsigned sourceFrame, double startTime, double finishTime);
-    virtual ~PerformanceRenderTiming();
+    ~PerformanceRenderTiming() override;
 
     unsigned m_sourceFrame;
     RefPtrWillBeMember<Document> m_requestingDocument;