Don't unconditionally create a LayoutObject for SVGMarkerElement.

third_party/WebKit/Source/core/svg/SVGMarkerElement.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Nikolas Zimmermann
  * <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006 Rob Buis <buis@kde.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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 70 matching lines @@
 
  private:
   explicit SVGMarkerElement(Document&);
 
   bool needsPendingResourceHandling() const override { return false; }
 
   void svgAttributeChanged(const QualifiedName&) override;
   void childrenChanged(const ChildrenChange&) override;
 
   LayoutObject* createLayoutObject(const ComputedStyle&) override;
-  bool layoutObjectIsNeeded(const ComputedStyle&) override { return true; }
+  bool layoutObjectIsNeeded(const ComputedStyle&) override;
 
   bool selfHasRelativeLengths() const override;
 
   Member<SVGAnimatedLength> m_refX;
   Member<SVGAnimatedLength> m_refY;
   Member<SVGAnimatedLength> m_markerWidth;
   Member<SVGAnimatedLength> m_markerHeight;
   Member<SVGAnimatedAngle> m_orientAngle;
   Member<SVGAnimatedEnumeration<SVGMarkerUnitsType>> m_markerUnits;
 };
 
 }  // namespace blink
 
 #endif  // SVGMarkerElement_h