Don't paint SVG image documents unless actually painting.

third_party/WebKit/Source/core/svg/graphics/SVGImage.cpp

 /*
  * Copyright (C) 2006 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. 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.
@@ skipping 473 matching lines @@
 
   // serviceScriptedAnimations runs requestAnimationFrame callbacks, but SVG
   // images can't have any so we assert there's no script.
   ScriptForbiddenScope forbidScript;
 
   // The calls below may trigger GCs, so set up the required persistent
   // reference on the ImageResource which owns this SVGImage. By transitivity,
   // that will keep the associated SVGImageChromeClient object alive.
   Persistent<ImageObserver> protect(getImageObserver());
   m_page->animator().serviceScriptedAnimations(monotonicAnimationStartTime);
-  m_page->animator().updateAllLifecyclePhases(
-      *toLocalFrame(m_page->mainFrame()));
+  // Do *not* update the paint phase. It's critical to paint only when
+  // actually generating painted output, not only for performance reasons,
+  // but to preserve correct coherence of the cache of the output with
+  // the needsRepaint bits of the PaintLayers in the image.
+  toLocalFrame(m_page->mainFrame())
+      ->view()
+      ->updateAllLifecyclePhasesExceptPaint();
 }
 
 void SVGImage::advanceAnimationForTesting() {
   if (SVGSVGElement* rootElement = svgRootElement(m_page.get())) {
     rootElement->timeContainer()->advanceFrameForTesting();
 
     // The following triggers animation updates which can issue a new draw
     // but will not permanently change the animation timeline.
     // TODO(pdr): Actually advance the document timeline so CSS animations
     // can be properly tested.
@@ skipping 111 matching lines @@
   }
 
   return m_page ? SizeAvailable : SizeUnavailable;
 }
 
 String SVGImage::filenameExtension() const {
   return "svg";
 }
 
 }  // namespace blink