[S.P.] Don't draw frames of animated images that are offscreen.

Source/core/layout/LayoutImage.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2006 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011 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
@@ skipping 65 matching lines @@
 
     virtual void imageChanged(WrappedImagePtr, const IntRect* = 0) override;
 
     virtual void paint(const PaintInfo&, const LayoutPoint&) override final;
 
     virtual void layout() override;
     virtual bool updateImageLoadingPriorities() override final;
 
     virtual bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectLayoutImage || LayoutReplaced::isOfType(type); }
 
+    virtual PaintInvalidationReason invalidatePaintIfNeeded(const PaintInvalidationState&, const LayoutBoxModelObject&) override;
+
 private:
     virtual bool isImage() const override { return true; }
 
     virtual void paintReplaced(const PaintInfo&, const LayoutPoint&) override;
 
     virtual bool foregroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect, unsigned maxDepthToTest) const override final;
     virtual bool computeBackgroundIsKnownToBeObscured() override final;
 
     virtual bool backgroundShouldAlwaysBeClipped() const override { return true; }
 
     virtual LayoutUnit minimumReplacedHeight() const override;
 
     virtual void notifyFinished(Resource*) override final;
     virtual bool nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction) override final;
 
     virtual bool boxShadowShouldBeAppliedToBackground(BackgroundBleedAvoidance, InlineFlowBox*) const override final;
 
     void invalidatePaintAndMarkForLayoutIfNeeded();
     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();
 
+    // The given rect is in the local coordinate space of the LayoutImage.
+    bool rectIntersectsVisibleViewport(const LayoutRect&);
+
     // Text to display as long as the image isn't available.
     OwnPtr<LayoutImageResource> m_imageResource;
     bool m_didIncrementVisuallyNonEmptyPixelCount;
     bool m_isGeneratedContent;
     float m_imageDevicePixelRatio;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutImage, isLayoutImage());
 
 } // namespace blink
 
 #endif // LayoutImage_h