Reland of HTMLImageElement: do not use fallback content for ImageDocument

third_party/WebKit/Source/core/html/HTMLImageElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 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 715 matching lines @@
     if (!foundURL) {
         candidate = bestFitSourceForImageAttributes(document().devicePixelRatio(), sourceSize(*this), fastGetAttribute(srcAttr), fastGetAttribute(srcsetAttr), &document());
         setBestFitURLAndDPRFromImageCandidate(candidate);
     }
     imageLoader().updateFromElement(behavior, m_referrerPolicy);
 
     // Images such as data: uri's can return immediately and may already have errored out.
     bool imageHasLoaded = imageLoader().image() && !imageLoader().image()->isLoading() && !imageLoader().image()->errorOccurred();
     bool imageStillLoading = !imageHasLoaded && imageLoader().hasPendingActivity() && !imageLoader().hasPendingError() && !imageSourceURL().isEmpty();
     bool imageHasImage = imageLoader().image() && imageLoader().image()->hasImage();
+    bool imageIsDocument = imageLoader().isLoadingImageDocument() && imageLoader().image() && !imageLoader().image()->errorOccurred();
 
     // Icky special case for deferred images:
     // A deferred image is not loading, does have pending activity, does not
     // have an error, but it does have an ImageResource associated
     // with it, so imageHasLoaded will be true even though the image hasn't
     // actually loaded. Fixing the definition of imageHasLoaded isn't
     // sufficient, because a deferred image does have pending activity, does not
     // have a pending error, and does have a source URL, so if imageHasLoaded
     // was correct, imageStillLoading would become wrong.
     //
     // Instead of dealing with that, there's a separate check that the
     // ImageResource has non-null image data associated with it, which isn't
     // folded into imageHasLoaded above.
-    if ((imageHasLoaded && imageHasImage) || imageStillLoading)
+    if ((imageHasLoaded && imageHasImage) || imageStillLoading || imageIsDocument)
         ensurePrimaryContent();
     else
         ensureFallbackContent();
 }
 
 const KURL& HTMLImageElement::sourceURL() const
 {
     return cachedImage()->response().url();
 }
 
@@ skipping 80 matching lines @@
 {
     ImageResource* image = cachedImage();
     if (!image)
         return IntSize();
     LayoutSize lSize = image->imageSize(LayoutObject::shouldRespectImageOrientation(layoutObject()), 1.0f);
     DCHECK(lSize.fraction().isZero());
     return IntSize(lSize.width().toInt(), lSize.height().toInt());
 }
 
 } // namespace blink