Mark children of an SVG root as needing paint invalidation checking on resize.

third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp

 /*
  * Copyright (C) 2004, 2005, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2007, 2008, 2009 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Google, Inc.
  * Copyright (C) Research In Motion Limited 2011. 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 139 matching lines @@
     m_didScreenScaleFactorChange = selfNeedsLayout();
 
     SVGLayoutSupport::layoutResourcesIfNeeded(this);
 
     SVGSVGElement* svg = toSVGSVGElement(node());
     ASSERT(svg);
     // When hasRelativeLengths() is false, no descendants have relative lengths
     // (hence no one is interested in viewport size changes).
     m_isLayoutSizeChanged = svg->hasRelativeLengths() && (selfNeedsLayout() || oldSize != size());
 
+    // The scale of one or more of the SVG elements may have changed, so mark
+    // the entire subtree as needing paint invalidation checking.
+    if (m_isLayoutSizeChanged)
+        setMayNeedPaintInvalidationSubtree();
+
     SVGLayoutSupport::layoutChildren(firstChild(), false, m_didScreenScaleFactorChange, m_isLayoutSizeChanged);
 
     if (m_needsBoundariesOrTransformUpdate) {
         updateCachedBoundaries();
         m_needsBoundariesOrTransformUpdate = false;
     }
 
     m_overflow.reset();
     addVisualEffectOverflow();
 
@@ skipping 248 matching lines @@
             updateHitTestResult(result, pointInBorderBox);
             if (result.addNodeToListBasedTestResult(node(), locationInContainer, boundsRect) == StopHitTesting)
                 return true;
         }
     }
 
     return false;
 }
 
 } // namespace blink