Followup fixes for bug 332066.

Source/core/svg/SVGUseElement.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 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 40 matching lines @@
     SVGAnimatedLength* x() const { return m_x.get(); }
     SVGAnimatedLength* y() const { return m_y.get(); }
     SVGAnimatedLength* width() const { return m_width.get(); }
     SVGAnimatedLength* height() const { return m_height.get(); }
 
     virtual void buildPendingResource() OVERRIDE;
 
 private:
     SVGUseElement(Document&, bool wasInsertedByParser);
 
-    virtual bool isStructurallyExternal() const OVERRIDE { return isExternalURIReference(hrefCurrentValue(), document()); }
+    virtual bool isStructurallyExternal() const OVERRIDE { return !hrefCurrentValue().isNull() && isExternalURIReference(hrefCurrentValue(), document()); }
+
     virtual bool supportsFocus() const OVERRIDE { return hasFocusEventListeners(); }
 
     virtual InsertionNotificationRequest insertedInto(ContainerNode*) OVERRIDE;
     virtual void removedFrom(ContainerNode*) OVERRIDE;
 
     bool isSupportedAttribute(const QualifiedName&);
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
     virtual void svgAttributeChanged(const QualifiedName&) OVERRIDE;
 
     virtual RenderObject* createRenderer(RenderStyle*) OVERRIDE;
     virtual void toClipPath(Path&) OVERRIDE;
 
     void clearResourceReferences();
     void buildShadowAndInstanceTree(SVGElement* target);
     void detachInstance();
 
     void scheduleShadowTreeRecreation();
-
-    virtual bool haveLoadedRequiredResources() OVERRIDE { return m_haveFiredLoadEvent; }
+    virtual bool haveLoadedRequiredResources() OVERRIDE { return !isStructurallyExternal() || m_haveFiredLoadEvent; }
 
     virtual void finishParsingChildren() OVERRIDE;
     virtual bool selfHasRelativeLengths() const OVERRIDE;
 
     // Instance tree handling
     void buildInstanceTree(SVGElement* target, SVGElementInstance* targetInstance, bool& foundCycle, bool foundUse);
     bool hasCycleUseReferencing(SVGUseElement*, SVGElementInstance* targetInstance, SVGElement*& newTarget);
 
     // Shadow tree handling
     void buildShadowTree(SVGElement* target, SVGElementInstance* targetInstance);
@@ skipping 31 matching lines @@
     RefPtr<SVGElementInstance> m_targetElementInstance;
     ResourcePtr<DocumentResource> m_resource;
     Timer<SVGElement> m_svgLoadEventTimer;
 };
 
 DEFINE_NODE_TYPE_CASTS(SVGUseElement, hasTagName(SVGNames::useTag));
 
 }
 
 #endif