Clean up virtual functions in css/

Source/core/css/CSSViewportRule.h

Index: Source/core/css/CSSViewportRule.h
diff --git a/Source/core/css/CSSViewportRule.h b/Source/core/css/CSSViewportRule.h
index 64a9b867cfc127faee6c49b3ad1f9703b29efd72..daf8987c4556b50dee4e7e8fe3a9534b1fa7dc33 100644
--- a/Source/core/css/CSSViewportRule.h
+++ b/Source/core/css/CSSViewportRule.h
@@ -49,7 +49,6 @@ public:
     }
     virtual ~CSSViewportRule();
 
-    virtual CSSRule::Type type() const override { return VIEWPORT_RULE; }
     virtual String cssText() const override;
     virtual void reattach(StyleRuleBase*) override;
 
@@ -60,6 +59,8 @@ public:
 private:
     CSSViewportRule(StyleRuleViewport*, CSSStyleSheet*);
 
+    virtual CSSRule::Type type() const override { return VIEWPORT_RULE; }
+
     RefPtrWillBeMember<StyleRuleViewport> m_viewportRule;
     mutable RefPtrWillBeMember<StyleRuleCSSStyleDeclaration> m_propertiesCSSOMWrapper;
 };