Make brokenImage() a static member of ImageResource class

Source/core/fetch/ImageResource.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007 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 37 matching lines @@
     ImageResource(WebCore::Image*);
     virtual ~ImageResource();
 
     virtual void load(ResourceFetcher*, const ResourceLoaderOptions&);
 
     WebCore::Image* image(); // Returns the nullImage() if the image is not available yet.
     WebCore::Image* imageForRenderer(const RenderObject*); // Returns the nullImage() if the image is not available yet.
     bool hasImage() const { return m_image.get(); }
     bool currentFrameKnownToBeOpaque(const RenderObject*); // Side effect: ensures decoded image is in cache, therefore should only be called when about to draw the image.
 
-    std::pair<WebCore::Image*, float> brokenImage(float deviceScaleFactor) const; // Returns an image and the image's resolution scale factor.
+    static std::pair<WebCore::Image*, float> brokenImage(float deviceScaleFactor); // Returns an image and the image's resolution scale factor.
     bool willPaintBrokenImage() const;
 
     bool canRender(const RenderObject* renderer, float multiplier) { return !errorOccurred() && !imageSizeForRenderer(renderer, multiplier).isEmpty(); }
 
     void setContainerSizeForRenderer(const ImageResourceClient*, const IntSize&, float);
     bool usesImageContainerSize() const;
     bool imageHasRelativeWidth() const;
     bool imageHasRelativeHeight() const;
 
     // This method takes a zoom multiplier that can be used to increase the natural size of the image by the zoom.
@@ skipping 42 matching lines @@
     ContainerSizeRequests m_pendingContainerSizeRequests;
 
     RefPtr<WebCore::Image> m_image;
     OwnPtr<SVGImageCache> m_svgImageCache;
     bool m_loadingMultipartContent;
 };
 
 }
 
 #endif