Begin tracking why layout is invalidated

Source/core/svg/SVGGradientElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) Research In Motion Limited 2010. 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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 79 matching lines @@
 }
 
 void SVGGradientElement::childrenChanged(const ChildrenChange& change)
 {
     SVGElement::childrenChanged(change);
 
     if (change.byParser)
         return;
 
     if (LayoutObject* object = layoutObject())
-        object->setNeedsLayoutAndFullPaintInvalidation();
+        object->setNeedsLayoutAndFullPaintInvalidation(LayoutInvalidationReason::ChildChanged);
 }
 
 Vector<Gradient::ColorStop> SVGGradientElement::buildStops()
 {
     Vector<Gradient::ColorStop> stops;
 
     float previousOffset = 0.0f;
     for (SVGStopElement* stop = Traversal<SVGStopElement>::firstChild(*this); stop; stop = Traversal<SVGStopElement>::nextSibling(*stop)) {
         // Figure out right monotonic offset
         float offset = stop->offset()->currentValue()->value();
         offset = std::min(std::max(previousOffset, offset), 1.0f);
         previousOffset = offset;
 
         stops.append(Gradient::ColorStop(offset, stop->stopColorIncludingOpacity()));
     }
 
     return stops;
 }
 
 }