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

Source/core/page/PageSerializer.cpp

Index: Source/core/page/PageSerializer.cpp
diff --git a/Source/core/page/PageSerializer.cpp b/Source/core/page/PageSerializer.cpp
index 30462b3f66ec911d8577cd6206e25481aa66162a..871444f0509f18359eae7ddef841dc09855074ee 100644
--- a/Source/core/page/PageSerializer.cpp
+++ b/Source/core/page/PageSerializer.cpp
@@ -103,15 +103,15 @@ class SerializerMarkupAccumulator : public MarkupAccumulator {
     STACK_ALLOCATED();
 public:
     SerializerMarkupAccumulator(PageSerializer*, const Document&, WillBeHeapVector<RawPtrWillBeMember<Node>>&);
-    virtual ~SerializerMarkupAccumulator();
+    ~SerializerMarkupAccumulator() override;
 
 protected:
-    virtual void appendText(StringBuilder& out, Text&) override;
-    virtual bool shouldIgnoreAttribute(const Attribute&) override;
-    virtual void appendElement(StringBuilder& out, Element&, Namespaces*) override;
-    virtual void appendCustomAttributes(StringBuilder& out, const Element&, Namespaces*) override;
-    virtual void appendStartTag(Node&, Namespaces* = nullptr) override;
-    virtual void appendEndTag(const Element&) override;
+    void appendText(StringBuilder& out, Text&) override;
+    bool shouldIgnoreAttribute(const Attribute&) override;
+    void appendElement(StringBuilder& out, Element&, Namespaces*) override;
+    void appendCustomAttributes(StringBuilder& out, const Element&, Namespaces*) override;
+    void appendStartTag(Node&, Namespaces* = nullptr) override;
+    void appendEndTag(const Element&) override;
 
     const Document& document();