Fix textpath is not displayed on use element

third_party/WebKit/Source/core/layout/svg/LayoutSVGTextPath.cpp

 /*
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 42 matching lines @@
 {
     if (child->isText())
         return SVGLayoutSupport::isLayoutableTextNode(child);
 
     return child->isSVGInline() && !child->isSVGTextPath();
 }
 
 PassOwnPtr<PathPositionMapper> LayoutSVGTextPath::layoutPath() const
 {
     const SVGTextPathElement& textPathElement = toSVGTextPathElement(*node());
-    Element* targetElement = SVGURIReference::targetElementFromIRIString(
-        textPathElement.hrefString(), textPathElement.treeScope());
+    Element* targetElement;
+    if (textPathElement.inUseShadowTree()) {

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

I think we could simplify this a bit (and preferably move it to a helper so that
we can pick one TreeScope& or the other:

TreeScope& treeScopeForIdResolution(SVGElement& element)
{
    if (SVGElement* correspondingElement = element.correspondingElement())
        return correspondingElement->treeScope();
    return element.treeScope();
}

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

Done.

+        SVGElement* correspondingElement = textPathElement.correspondingElement();
+        if (correspondingElement && isSVGTextPathElement(correspondingElement)) {
+            targetElement = SVGURIReference::targetElementFromIRIString(
+                textPathElement.hrefString(), correspondingElement->treeScope());
+        }
+    } else {
+        targetElement = SVGURIReference::targetElementFromIRIString(
+            textPathElement.hrefString(), textPathElement.treeScope());
+    }
     if (!isSVGPathElement(targetElement))
         return nullptr;
 
     SVGPathElement& pathElement = toSVGPathElement(*targetElement);
     Path pathData = pathElement.asPath();
     if (pathData.isEmpty())
         return nullptr;
 
     // Spec:  The transform attribute on the referenced 'path' element represents a
     // supplemental transformation relative to the current user coordinate system for
     // the current 'text' element, including any adjustments to the current user coordinate
     // system due to a possible transform attribute on the current 'text' element.
     // http://www.w3.org/TR/SVG/text.html#TextPathElement
     pathData.transform(pathElement.calculateAnimatedLocalTransform());
 
     return PathPositionMapper::create(pathData);
 }
 
 float LayoutSVGTextPath::calculateStartOffset(float pathLength) const
 {
     const SVGLength& startOffset = *toSVGTextPathElement(node())->startOffset()->currentValue();
     float textPathStartOffset = startOffset.valueAsPercentage();
     if (startOffset.typeWithCalcResolved() == CSSPrimitiveValue::UnitType::Percentage)
         textPathStartOffset *= pathLength;
 
     return textPathStartOffset;
 }
 
 } // namespace blink