Hoist "layout size changed" check out of SVGLayoutSupport::layoutChildren

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 133 matching lines @@
     LayoutSize oldSize = size();
     updateLogicalWidth();
     updateLogicalHeight();
     buildLocalToBorderBoxTransform();
 
     SVGLayoutSupport::layoutResourcesIfNeeded(this);
 
     SVGSVGElement* svg = toSVGSVGElement(node());
     ASSERT(svg);
     m_isLayoutSizeChanged = needsLayout || (svg->hasRelativeLengths() && oldSize != size());
+    // When hasRelativeLengths() is false, no descendants have relative lengths
+    // (hence no one is interested in viewport size changes).
+    bool layoutSizeChanged = m_isLayoutSizeChanged && svg->hasRelativeLengths();
+
     // If any of this root's children need to be laid out, and a filter is
     // applied to it, we need to issue paint invalidations for all descendants.
     bool forceLayoutOfChildren = needsLayout
         || (normalChildNeedsLayout() && SVGLayoutSupport::hasFilterResource(*this));
+
     const bool transformToRootChanged = false;
-    SVGLayoutSupport::layoutChildren(this, forceLayoutOfChildren, transformToRootChanged);
+    SVGLayoutSupport::layoutChildren(this, forceLayoutOfChildren, transformToRootChanged, layoutSizeChanged);
 
     if (m_needsBoundariesOrTransformUpdate) {
         updateCachedBoundaries();
         m_needsBoundariesOrTransformUpdate = false;
     }
 
     m_overflow.clear();
     addVisualEffectOverflow();
 
     if (!shouldApplyViewportClip()) {
@@ skipping 239 matching lines @@
             updateHitTestResult(result, pointInBorderBox);
             if (result.addNodeToListBasedTestResult(node(), locationInContainer, boundsRect) == StopHitTesting)
                 return true;
         }
     }
 
     return false;
 }
 
 } // namespace blink