Fix virtual/override/final usage in Source/core/layout/.

Source/core/layout/LayoutScrollbar.h

Index: Source/core/layout/LayoutScrollbar.h
diff --git a/Source/core/layout/LayoutScrollbar.h b/Source/core/layout/LayoutScrollbar.h
index f60e790e2527b436660dcb8098d76665cec80ba7..c23d0278093424ab9927013d13445bc35b25d5ee 100644
--- a/Source/core/layout/LayoutScrollbar.h
+++ b/Source/core/layout/LayoutScrollbar.h
@@ -42,7 +42,7 @@ class ComputedStyle;
 class LayoutScrollbar final : public Scrollbar {
 public:
     static PassRefPtrWillBeRawPtr<Scrollbar> createCustomScrollbar(ScrollableArea*, ScrollbarOrientation, Node*, LocalFrame* owningFrame = nullptr);
-    virtual ~LayoutScrollbar();
+    ~LayoutScrollbar() override;
 
     LayoutBox* owningLayoutObject() const;
 
@@ -52,11 +52,11 @@ public:
 
     int minimumThumbLength();
 
-    virtual bool isOverlayScrollbar() const override { return false; }
+    bool isOverlayScrollbar() const override { return false; }
 
     LayoutScrollbarPart* getPart(ScrollbarPart partType) { return m_parts.get(partType); }
 
-    virtual void invalidateRect(const IntRect&) override;
+    void invalidateRect(const IntRect&) override;
 
     DECLARE_VIRTUAL_TRACE();
 
@@ -66,15 +66,15 @@ protected:
 private:
     friend class Scrollbar;
 
-    virtual void setParent(Widget*) override;
-    virtual void setEnabled(bool) override;
+    void setParent(Widget*) override;
+    void setEnabled(bool) override;
 
-    virtual void setHoveredPart(ScrollbarPart) override;
-    virtual void setPressedPart(ScrollbarPart) override;
+    void setHoveredPart(ScrollbarPart) override;
+    void setPressedPart(ScrollbarPart) override;
 
-    virtual void styleChanged() override;
+    void styleChanged() override;
 
-    virtual bool isCustomScrollbar() const override { return true; }
+    bool isCustomScrollbar() const override { return true; }
 
     void updateScrollbarParts(bool destroy = false);