Fix textpath is not displayed on use element

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

 /*
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2010 Rob Buis <rwlbuis@gmail.com>
  *
  * 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 106 matching lines @@
     return false;
 }
 
 void SVGTextPathElement::buildPendingResource()
 {
     clearResourceReferences();
     if (!inDocument())
         return;
 
     AtomicString id;
-    Element* target = SVGURIReference::targetElementFromIRIString(hrefString(), treeScope(), &id);
+    Element* target = nullptr;
+
+    if (inUseShadowTree()) {

[fs, 2016/03/14 12:54:10]

Not sure this is actually needed. When the "real" element changes it will notify
the instance - which will then update. If anything we should probably just do
nothing here if this is an instance...

[hyunjunekim2, 2016/03/15 23:11:32]

Change before.

+        SVGElement* correspondingElement = this->correspondingElement();
+        if (correspondingElement)
+            target = SVGURIReference::targetElementFromIRIString(hrefString(), correspondingElement->treeScope(), &id);
+    } else {
+        target = SVGURIReference::targetElementFromIRIString(hrefString(), treeScope(), &id);
+    }
+
     if (!target) {
         // Do not register as pending if we are already pending this resource.
         if (document().accessSVGExtensions().isElementPendingResource(this, id))
             return;
 
         if (!id.isEmpty()) {
             document().accessSVGExtensions().addPendingResource(id, this);
             ASSERT(hasPendingResources());
         }
     } else if (isSVGPathElement(*target)) {
@@ skipping 17 matching lines @@
         clearResourceReferences();
 }
 
 bool SVGTextPathElement::selfHasRelativeLengths() const
 {
     return m_startOffset->currentValue()->isRelative()
         || SVGTextContentElement::selfHasRelativeLengths();
 }
 
 } // namespace blink