Oilpan: disable conservative GCs during initial GC mixin construction.

Source/core/svg/SVGSVGElement.h

 /*
  * Copyright (C) 2004, 2005, 2006 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2010 Rob Buis <buis@kde.org>
  * Copyright (C) 2014 Google, Inc.
  *
  * 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.
  *
@@ skipping 27 matching lines @@
 class SVGNumberTearOff;
 class SVGTransformTearOff;
 class SVGViewSpec;
 class SVGViewElement;
 class SMILTimeContainer;
 
 class SVGSVGElement final : public SVGGraphicsElement,
                             public SVGFitToViewBox,
                             public SVGZoomAndPan {
     DEFINE_WRAPPERTYPEINFO();
-    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(SVGSVGElement);
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN_NESTED(SVGSVGElement, SVGGraphicsElement);
 public:
     DECLARE_NODE_FACTORY(SVGSVGElement);
 
 #if !ENABLE(OILPAN)
     using SVGGraphicsElement::ref;
     using SVGGraphicsElement::deref;
 #endif
 
     // 'SVGSVGElement' functions
     PassRefPtrWillBeRawPtr<SVGRectTearOff> viewport() const;
@@ skipping 107 matching lines @@
     RefPtrWillBeMember<SMILTimeContainer> m_timeContainer;
     RefPtrWillBeMember<SVGPoint> m_translation;
     RefPtrWillBeMember<SVGViewSpec> m_viewSpec;
 
     friend class SVGCurrentTranslateTearOff;
 };
 
 } // namespace blink
 
 #endif // SVGSVGElement_h