Revert of Use Shadow DOM to display fallback content for images

Source/core/rendering/RenderImage.h

Index: Source/core/rendering/RenderImage.h
diff --git a/Source/core/rendering/RenderImage.h b/Source/core/rendering/RenderImage.h
index 445161c2c34aaae343538643d8531547ffb62bb3..4f0f596995acf0aed70815ba4be92ee3a61335dc 100644
--- a/Source/core/rendering/RenderImage.h
+++ b/Source/core/rendering/RenderImage.h
@@ -51,12 +51,18 @@
     const RenderImageResource* imageResource() const { return m_imageResource.get(); }
     ImageResource* cachedImage() const { return m_imageResource ? m_imageResource->cachedImage() : 0; }
 
+    bool setImageSizeForAltText(ImageResource* newImage = 0);
+
+    void updateAltText();
+
     HTMLMapElement* imageMap() const;
     void areaElementFocusChanged(HTMLAreaElement*);
 
     void setIsGeneratedContent(bool generated = true) { m_isGeneratedContent = generated; }
 
     bool isGeneratedContent() const { return m_isGeneratedContent; }
+
+    String altText() const { return m_altText; }
 
     inline void setImageDevicePixelRatio(float factor) { m_imageDevicePixelRatio = factor; }
     float imageDevicePixelRatio() const { return m_imageDevicePixelRatio; }
@@ -99,12 +105,14 @@
 
     virtual bool boxShadowShouldBeAppliedToBackground(BackgroundBleedAvoidance, InlineFlowBox*) const override final;
 
-    void repaintOrMarkForLayout(const IntRect* = 0);
+    IntSize imageSizeForError(ImageResource*) const;
+    void paintInvalidationOrMarkForLayout(bool imageSizeChanged, const IntRect* = 0);
     void updateIntrinsicSizeIfNeeded(const LayoutSize&);
     // Update the size of the image to be rendered. Object-fit may cause this to be different from the CSS box's content rect.
     void updateInnerContentRect();
 
     // Text to display as long as the image isn't available.
+    String m_altText;
     OwnPtr<RenderImageResource> m_imageResource;
     bool m_didIncrementVisuallyNonEmptyPixelCount;
     bool m_isGeneratedContent;