Don't require a valid reference scope for a <use> shadow tree update

Source/core/svg/SVGUseElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  * Copyright (C) 2011 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012 University of Szeged
  * Copyright (C) 2012 Renata Hodovan <reni@webkit.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 108 matching lines @@
 
 void SVGUseElement::removedFrom(ContainerNode* rootParent)
 {
     SVGGraphicsElement::removedFrom(rootParent);
     if (rootParent->inDocument())
         clearResourceReferences();
 }
 
 TreeScope* SVGUseElement::referencedScope() const
 {
-    if (!isExternalURIReference(hrefString(), document()))
-        return &treeScope();
-    return externalDocument();
+    if (isStructurallyExternal())
+        return externalDocument();
+    return &treeScope();
 }
 
 Document* SVGUseElement::externalDocument() const
 {
     if (m_resource && m_resource->isLoaded()) {
         // Gracefully handle error condition.
         if (m_resource->errorOccurred())
             return nullptr;
         ASSERT(m_resource->document());
         return m_resource->document();
@@ skipping 73 matching lines @@
         }
 
         LayoutObject* object = this->layoutObject();
         if (object)
             markForLayoutAndParentResourceInvalidation(object);
         return;
     }
 
     if (SVGURIReference::isKnownAttribute(attrName)) {
         SVGElement::InvalidationGuard invalidationGuard(this);
-        bool isExternalReference = isExternalURIReference(hrefString(), document());
-        if (isExternalReference) {
+        if (isStructurallyExternal()) {
             KURL url = document().completeURL(hrefString());
             if (url.hasFragmentIdentifier()) {
                 FetchRequest request(ResourceRequest(url), localName());
                 setDocumentResource(DocumentResource::fetchSVGDocument(request, document().fetcher()));
             }
         } else {
             setDocumentResource(0);
         }
 
         invalidateShadowTree();
@@ skipping 53 matching lines @@
     for (Node* cur = start->firstChild(); cur; cur = cur->nextSibling()) {
         if (subtreeContainsDisallowedElement(cur))
             return true;
     }
 
     return false;
 }
 
 void SVGUseElement::scheduleShadowTreeRecreation()
 {
-    if (!referencedScope() || inUseShadowTree())
+    if (inUseShadowTree())
         return;
     m_needsShadowTreeRecreation = true;
     document().scheduleUseShadowTreeUpdate(*this);
 }
 
 void SVGUseElement::clearResourceReferences()
 {
     if (m_targetElementInstance)
         m_targetElementInstance = nullptr;
 
     // FIXME: We should try to optimize this, to at least allow partial reclones.
     if (ShadowRoot* shadowTreeRootElement = userAgentShadowRoot())
         shadowTreeRootElement->removeChildren(OmitSubtreeModifiedEvent);
 
     m_needsShadowTreeRecreation = false;
     document().unscheduleUseShadowTreeUpdate(*this);
 
     removeAllOutgoingReferences();
 }
 
 void SVGUseElement::buildPendingResource()
 {
-    if (!referencedScope() || inUseShadowTree())
+    if (inUseShadowTree())
         return;
     clearResourceReferences();
-    if (!inDocument())
+    if (!referencedScope() || !inDocument())
         return;
 
     AtomicString id;
     Element* target = SVGURIReference::targetElementFromIRIString(hrefString(), treeScope(), &id, externalDocument());
     if (!target || !target->inDocument()) {
         // If we can't find the target of an external element, just give up.
         // We can't observe if the target somewhen enters the external document, nor should we do it.
         if (externalDocument())
             return;
         if (id.isEmpty())
@@ skipping 446 matching lines @@
 
     if (m_resource)
         m_resource->removeClient(this);
 
     m_resource = resource;
     if (m_resource)
         m_resource->addClient(this);
 }
 
 }