Initialize GC mixin bases only when leftmost vtable has been initialized.

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 31 matching lines @@
     DEFINE_STATIC_LOCAL(SVGEnumerationStringEntries, entries, ());
     if (entries.isEmpty()) {
         entries.append(std::make_pair(SVGTextPathSpacingAuto, "auto"));
         entries.append(std::make_pair(SVGTextPathSpacingExact, "exact"));
     }
     return entries;
 }
 
 inline SVGTextPathElement::SVGTextPathElement(Document& document)
     : SVGTextContentElement(SVGNames::textPathTag, document)
-    , SVGURIReference(this)
     , m_startOffset(SVGAnimatedLength::create(this, SVGNames::startOffsetAttr, SVGLength::create(LengthModeOther), AllowNegativeLengths))
     , m_method(SVGAnimatedEnumeration<SVGTextPathMethodType>::create(this, SVGNames::methodAttr, SVGTextPathMethodAlign))
     , m_spacing(SVGAnimatedEnumeration<SVGTextPathSpacingType>::create(this, SVGNames::spacingAttr, SVGTextPathSpacingExact))
 {
+    SVGURIReference::initialize(this);
+
     addToPropertyMap(m_startOffset);
     addToPropertyMap(m_method);
     addToPropertyMap(m_spacing);
 }
 
 DEFINE_NODE_FACTORY(SVGTextPathElement)
 
 SVGTextPathElement::~SVGTextPathElement()
 {
 #if !ENABLE(OILPAN)
@@ skipping 99 matching lines @@
         clearResourceReferences();
 }
 
 bool SVGTextPathElement::selfHasRelativeLengths() const
 {
     return m_startOffset->currentValue()->isRelative()
         || SVGTextContentElement::selfHasRelativeLengths();
 }
 
 } // namespace blink