Update rendering classes to use OVERRIDE / FINAL when needed

Source/core/rendering/RenderSlider.h

Index: Source/core/rendering/RenderSlider.h
diff --git a/Source/core/rendering/RenderSlider.h b/Source/core/rendering/RenderSlider.h
index a627e2c0489c67c690e20ba5d07d8dc1d286ebea..5163adaa71c0b4a63a0a85f57a64fd15dcc8d785 100644
--- a/Source/core/rendering/RenderSlider.h
+++ b/Source/core/rendering/RenderSlider.h
@@ -39,13 +39,13 @@ public:
     bool inDragMode() const;
 
 private:
-    virtual const char* renderName() const { return "RenderSlider"; }
-    virtual bool isSlider() const { return true; }
+    virtual const char* renderName() const OVERRIDE { return "RenderSlider"; }
+    virtual bool isSlider() const OVERRIDE { return true; }
 
-    virtual int baselinePosition(FontBaseline, bool firstLine, LineDirectionMode, LinePositionMode = PositionOnContainingLine) const;
+    virtual int baselinePosition(FontBaseline, bool firstLine, LineDirectionMode, LinePositionMode = PositionOnContainingLine) const OVERRIDE;
     virtual void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const OVERRIDE;
     virtual void computePreferredLogicalWidths() OVERRIDE;
-    virtual void layout();
+    virtual void layout() OVERRIDE;
 
     SliderThumbElement* sliderThumbElement() const;
 };