DO NOT SUBMIT really old prototype of sprite recognition for image replacement

third_party/WebKit/Source/core/loader/ImageLoader.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010 Apple 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 274 matching lines @@
         }
 
         if (referrerPolicy != ReferrerPolicyDefault)
             resourceRequest.setHTTPReferrer(SecurityPolicy::generateReferrer(referrerPolicy, url, document.outgoingReferrer()));
 
         if (isHTMLPictureElement(element()->parentNode()) || !element()->fastGetAttribute(HTMLNames::srcsetAttr).isNull())
             resourceRequest.setRequestContext(WebURLRequest::RequestContextImageSet);
         FetchRequest request(resourceRequest, element()->localName(), resourceLoaderOptions);
         configureRequest(request, bypassBehavior, *m_element, document.clientHintsPreferences());
 
-        newImage = ImageResource::fetch(request, document.fetcher());
+        ImageResource::PlaceholderRequestType placeholderRequestType = document.settings() && document.settings()->fetchImagePlaceholders() && updateBehavior != UpdateForcedReload
+            ? ImageResource::PlaceholderRequestType::AllowPlaceholder
+            : ImageResource::PlaceholderRequestType::DisallowPlaceholder;
+        newImage = ImageResource::fetch(request, document.fetcher(), placeholderRequestType);
 
         if (!newImage && !pageIsBeingDismissed(&document)) {
             crossSiteOrCSPViolationOccurred(imageSourceURL);
             dispatchErrorEvent();
         } else {
             clearFailedLoadURL();
         }
     } else {
         if (!imageSourceURL.isNull()) {
             // Fire an error event if the url string is not empty, but the KURL is.
@@ skipping 299 matching lines @@
 
 void ImageLoader::elementDidMoveToNewDocument()
 {
     if (m_loadDelayCounter)
         m_loadDelayCounter->documentChanged(m_element->document());
     clearFailedLoadURL();
     setImage(0);
 }
 
 } // namespace blink