Re-instate geometry sharing optimization for 'd' on <use>'d <path>s

third_party/WebKit/Source/core/svg/SVGPathElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 134 matching lines @@
             markForLayoutAndParentResourceInvalidation(layoutObject());
         return;
     }
 
     SVGGeometryElement::svgAttributeChanged(attrName);
 }
 
 void SVGPathElement::collectStyleForPresentationAttribute(const QualifiedName& name, const AtomicString& value, MutableStylePropertySet* style)
 {
     SVGAnimatedPropertyBase* property = propertyFromAttribute(name);
-    if (property == m_path)
-        addPropertyToPresentationAttributeStyle(style, CSSPropertyD, m_path->currentValue()->pathValue());
-    else
-        SVGGeometryElement::collectStyleForPresentationAttribute(name, value, style);
+    if (property == m_path) {
+        SVGAnimatedPath* path = this->path();
+        // If this is a <use> instance, return the referenced path to maximize geometry sharing.
+        if (const SVGElement* element = correspondingElement())
+            path = toSVGPathElement(element)->path();
+        addPropertyToPresentationAttributeStyle(style, CSSPropertyD, path->currentValue()->pathValue());
+        return;
+    }
+    SVGGeometryElement::collectStyleForPresentationAttribute(name, value, style);
 }
 
 void SVGPathElement::invalidateMPathDependencies()
 {
     // <mpath> can only reference <path> but this dependency is not handled in
     // markForLayoutAndParentResourceInvalidation so we update any mpath dependencies manually.
     if (SVGElementSet* dependencies = setOfIncomingReferences()) {
         for (SVGElement* element : *dependencies) {
             if (isSVGMPathElement(*element))
                 toSVGMPathElement(element)->targetPathChanged();
         }
     }
 }
 
 Node::InsertionNotificationRequest SVGPathElement::insertedInto(ContainerNode* rootParent)
 {
     SVGGeometryElement::insertedInto(rootParent);
     invalidateMPathDependencies();
     return InsertionDone;
 }
 
 void SVGPathElement::removedFrom(ContainerNode* rootParent)
 {
     SVGGeometryElement::removedFrom(rootParent);
     invalidateMPathDependencies();
 }
 
 } // namespace blink