Allow zoom/restore in a zoomed document. It is a regression from an earlier fix.

Source/core/html/ImageDocument.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 22 matching lines @@
 class ImageResource;
 class HTMLImageElement;
 
 class ImageDocument FINAL : public HTMLDocument {
 public:
     static PassRefPtr<ImageDocument> create(const DocumentInit& initializer = DocumentInit())
     {
         return adoptRef(new ImageDocument(initializer));
     }
 
+    enum ScaleType {
+        ScaleZoomedDocument,
+        ScaleOnlyUnzoomedDocument
+    };
+
     ImageResource* cachedImage();
     HTMLImageElement* imageElement() const { return m_imageElement.get(); }
 
-    void windowSizeChanged();
+    void windowSizeChanged(ScaleType);
     void imageUpdated();
     void imageClicked(int x, int y);
 
 private:
     ImageDocument(const DocumentInit&);
 
     virtual PassRefPtr<DocumentParser> createParser() OVERRIDE;
     virtual void dispose() OVERRIDE;
 
     void createDocumentStructure();
-    void resizeImageToFit();
-    void restoreImageSize();
+    void resizeImageToFit(ScaleType);
+    void restoreImageSize(ScaleType);
     bool imageFitsInWindow() const;
     bool shouldShrinkToFit() const;
     float scale() const;
 
     RefPtr<HTMLImageElement> m_imageElement;
 
     // Whether enough of the image has been loaded to determine its size
     bool m_imageSizeIsKnown;
 
     // Whether the image is shrunk to fit or not
     bool m_didShrinkImage;
 
     // Whether the image should be shrunk or not
     bool m_shouldShrinkImage;
 };
 
 DEFINE_DOCUMENT_TYPE_CASTS(ImageDocument);
 
 }
 
 #endif // ImageDocument_h