Revert of Use Shadow DOM to display fallback content for images

Source/core/html/forms/ImageInputType.h

Index: Source/core/html/forms/ImageInputType.h
diff --git a/Source/core/html/forms/ImageInputType.h b/Source/core/html/forms/ImageInputType.h
index 0e20b90e706ffad8cc04a24b5a4b31745c8b1d7e..9d53891b4ba691f8e80b675a33f3d4c5738664d1 100644
--- a/Source/core/html/forms/ImageInputType.h
+++ b/Source/core/html/forms/ImageInputType.h
@@ -41,7 +41,6 @@
 class ImageInputType final : public BaseButtonInputType {
 public:
     static PassRefPtrWillBeRawPtr<InputType> create(HTMLInputElement&);
-    virtual PassRefPtr<RenderStyle> customStyleForRenderer(PassRefPtr<RenderStyle>);
 
 private:
     ImageInputType(HTMLInputElement&);
@@ -54,7 +53,6 @@
     virtual void handleDOMActivateEvent(Event*) override;
     virtual void altAttributeChanged() override;
     virtual void srcAttributeChanged() override;
-    virtual void valueAttributeChanged() override;
     virtual void startResourceLoading() override;
     virtual bool shouldRespectAlignAttribute() override;
     virtual bool canBeSuccessfulSubmitButton() override;
@@ -64,15 +62,8 @@
     virtual unsigned width() const override;
     virtual bool hasLegalLinkAttribute(const QualifiedName&) const override;
     virtual const QualifiedName& subResourceAttributeName() const override;
-    virtual void ensureFallbackContent() override;
-    virtual void ensurePrimaryContent() override;
-    virtual void createShadowSubtree() override;
-
-    void reattachFallbackContent();
-    void setUseFallbackContent();
 
     IntPoint m_clickLocation; // Valid only during HTMLFormElement::prepareForSubmission().
-    bool m_useFallbackContent;
 };
 
 } // namespace blink