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

Source/core/svg/SVGTests.cpp

 /*
  * Copyright (C) 2004, 2005, 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 12 matching lines @@
 #include "core/svg/SVGTests.h"
 
 #include "core/SVGNames.h"
 #include "core/dom/DOMImplementation.h"
 #include "core/frame/UseCounter.h"
 #include "core/svg/SVGElement.h"
 #include "platform/Language.h"
 
 namespace blink {
 
-SVGTests::SVGTests(SVGElement* contextElement)
-    : m_requiredFeatures(SVGStaticStringList::create(contextElement, SVGNames::requiredFeaturesAttr))
-    , m_requiredExtensions(SVGStaticStringList::create(contextElement, SVGNames::requiredExtensionsAttr))
-    , m_systemLanguage(SVGStaticStringList::create(contextElement, SVGNames::systemLanguageAttr))
+SVGTests::SVGTests()
 {
+}
+
+void SVGTests::initialize(SVGElement* contextElement)
+{
+    ASSERT(!m_requiredFeatures.get());
+    ASSERT(!m_requiredExtensions.get());
+    ASSERT(!m_systemLanguage.get());

[haraken, 2015/01/20 15:40:32]

.get() won't be needed.

[sof, 2015/01/20 19:02:50]

Done, dropped them from the asserts here.

     ASSERT(contextElement);
 
+    m_requiredFeatures = SVGStaticStringList::create(contextElement, SVGNames::requiredFeaturesAttr);
+    m_requiredExtensions = SVGStaticStringList::create(contextElement, SVGNames::requiredExtensionsAttr);
+    m_systemLanguage = SVGStaticStringList::create(contextElement, SVGNames::systemLanguageAttr);
+
     contextElement->addToPropertyMap(m_requiredFeatures);
     contextElement->addToPropertyMap(m_requiredExtensions);
     contextElement->addToPropertyMap(m_systemLanguage);
 }
 
 void SVGTests::trace(Visitor* visitor)
 {
     visitor->trace(m_requiredFeatures);
     visitor->trace(m_requiredExtensions);
     visitor->trace(m_systemLanguage);
@@ skipping 72 matching lines @@
 }
 
 void SVGTests::addSupportedAttributes(HashSet<QualifiedName>& supportedAttributes)
 {
     supportedAttributes.add(SVGNames::requiredFeaturesAttr);
     supportedAttributes.add(SVGNames::requiredExtensionsAttr);
     supportedAttributes.add(SVGNames::systemLanguageAttr);
 }
 
 }