Don't allow <stop> as layout tree child of <svg> or <g>

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 218 matching lines @@
         // Box decorations may have appeared/disappeared - recompute status.
         m_hasBoxDecorationBackground = calculateHasBoxDecorations();
     }
 
     LayoutReplaced::styleDidChange(diff, oldStyle);
     SVGResourcesCache::clientStyleChanged(this, diff, styleRef());
 }
 
 bool LayoutSVGRoot::isChildAllowed(LayoutObject* child, const LayoutStyle&) const
 {
-    return child->isSVG() && !(child->isSVGInline() || child->isSVGInlineText());
+    return child->isSVG() && !(child->isSVGInline() || child->isSVGInlineText() || child->isSVGGradientStop());
 }
 
 void LayoutSVGRoot::addChild(LayoutObject* child, LayoutObject* beforeChild)
 {
     LayoutReplaced::addChild(child, beforeChild);
     SVGResourcesCache::clientWasAddedToTree(child, child->styleRef());
 
     bool shouldIsolateDescendants = (child->isBlendingAllowed() && child->style()->hasBlendMode()) || child->hasNonIsolatedBlendingDescendants();
     if (shouldIsolateDescendants)
         descendantIsolationRequirementsChanged(DescendantIsolationRequired);
@@ skipping 175 matching lines @@
             updateHitTestResult(result, pointInBorderBox);
             if (!result.addNodeToListBasedTestResult(node(), request, locationInContainer, boundsRect))
                 return true;
         }
     }
 
     return false;
 }
 
 }