Avoid using forced layout to trigger paint invalidation for SVG containers

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

 /*
  * Copyright (C) 2004, 2005, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2007, 2008 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Google, Inc.  All rights reserved.
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  *
  * 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 37 matching lines @@
 
 void LayoutSVGContainer::layout()
 {
     ASSERT(needsLayout());
     LayoutAnalyzer::Scope analyzer(*this);
 
     // Allow LayoutSVGViewportContainer to update its viewport.
     calcViewport();
 
     // Allow LayoutSVGTransformableContainer to update its transform.
-    bool updatedTransform = calculateLocalTransform();
-    m_didScreenScaleFactorChange = updatedTransform || SVGLayoutSupport::screenScaleFactorChanged(parent());
+    unsigned updatedTransform = calculateLocalTransform();
+    m_didScreenScaleFactorChange =
+        (updatedTransform & ScaleChange) || SVGLayoutSupport::screenScaleFactorChanged(parent());
 
     // LayoutSVGViewportContainer needs to set the 'layout size changed' flag.
     determineIfLayoutSizeChanged();
 
     // When hasRelativeLengths() is false, no descendants have relative lengths
     // (hence no one is interested in viewport size changes).
     bool layoutSizeChanged = element()->hasRelativeLengths()
         && SVGLayoutSupport::layoutSizeOfNearestViewportChanged(this);
 
     SVGLayoutSupport::layoutChildren(firstChild(), false, m_didScreenScaleFactorChange, layoutSizeChanged);
@@ skipping 124 matching lines @@
             updateHitTestResult(result, localLayoutPoint);
             if (result.addNodeToListBasedTestResult(element(), localLayoutPoint) == StopHitTesting)
                 return true;
         }
     }
     // 16.4: "If there are no graphics elements whose relevant graphics content is under the pointer (i.e., there is no target element), the event is not dispatched."
     return false;
 }
 
 } // namespace blink