Remove WebPageSerialzier related code.

sky/engine/core/html/HTMLImageElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 88 matching lines @@
 
 private:
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) override;
 
     virtual void attach(const AttachContext& = AttachContext()) override;
     virtual RenderObject* createRenderer(RenderStyle*) override;
 
     virtual bool canStartSelection() const override;
 
     virtual bool isURLAttribute(const Attribute&) const override;
-    virtual bool hasLegalLinkAttribute(const QualifiedName&) const override;
-    virtual const QualifiedName& subResourceAttributeName() const override;
 
     virtual InsertionNotificationRequest insertedInto(ContainerNode*) override;
     virtual void removedFrom(ContainerNode*) override;
     virtual Image* imageContents() override;
 
     ImageCandidate findBestFitImageFromPictureParent();
     void setBestFitURLAndDPRFromImageCandidate(const ImageCandidate&);
     HTMLImageLoader& imageLoader() const { return *m_imageLoader; }
     void notifyViewportChanged();
     void createMediaQueryListIfDoesNotExist();
 
     OwnPtr<HTMLImageLoader> m_imageLoader;
     RefPtr<ViewportChangeListener> m_listener;
     CompositeOperator m_compositeOperator;
     AtomicString m_bestFitImageURL;
     float m_imageDevicePixelRatio;
     unsigned m_elementCreatedByParser : 1;
     // Intrinsic sizing is viewport dependant if the 'w' descriptor was used for the picked resource.
     unsigned m_intrinsicSizingViewportDependant : 1;
     // Effective size is viewport dependant if the sizes attribute's effective size used v* length units.
     unsigned m_effectiveSizeViewportDependant : 1;
 };
 
 } // namespace blink
 
 #endif // HTMLImageElement_h