Merge 143840

Source/WebCore/dom/TreeScopeAdopter.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 22 matching lines @@
 #include "NodeTraversal.h"
 #include "RenderStyle.h"
 #include "ShadowRoot.h"
 
 namespace WebCore {
 
 void TreeScopeAdopter::moveTreeToNewScope(Node* root) const
 {
     ASSERT(needsScopeChange());
 
+    m_oldScope->guardRef();
+
     // If an element is moved from a document and then eventually back again the collection cache for
     // that element may contain stale data as changes made to it will have updated the DOMTreeVersion
     // of the document it was moved to. By increasing the DOMTreeVersion of the donating document here
     // we ensure that the collection cache will be invalidated as needed when the element is moved back.
     Document* oldDocument = m_oldScope->documentScope();
     Document* newDocument = m_newScope->documentScope();
     bool willMoveToNewDocument = oldDocument != newDocument;
     if (oldDocument && willMoveToNewDocument)
         oldDocument->incDOMTreeVersion();
 
     for (Node* node = root; node; node = NodeTraversal::next(node, root)) {
-        node->setTreeScope(m_newScope);
+        updateTreeScope(node);
 
         if (willMoveToNewDocument)
             moveNodeToNewDocument(node, oldDocument, newDocument);
         else if (node->hasRareData()) {
             NodeRareData* rareData = node->rareData();
             if (rareData->nodeLists())
                 rareData->nodeLists()->adoptTreeScope();
         }
 
         if (!node->isElementNode())
             continue;
 
         if (node->hasSyntheticAttrChildNodes()) {
             const Vector<RefPtr<Attr> >& attrs = toElement(node)->attrNodeList();
             for (unsigned i = 0; i < attrs.size(); ++i)
                 moveTreeToNewScope(attrs[i].get());
         }
 
         for (ShadowRoot* shadow = node->youngestShadowRoot(); shadow; shadow = shadow->olderShadowRoot()) {
             shadow->setParentTreeScope(m_newScope);
             if (willMoveToNewDocument)
                 moveTreeToNewDocument(shadow, oldDocument, newDocument);
         }
     }
+
+    m_oldScope->guardDeref();
 }
 
 void TreeScopeAdopter::moveTreeToNewDocument(Node* root, Document* oldDocument, Document* newDocument) const
 {
     for (Node* node = root; node; node = NodeTraversal::next(node, root)) {
         moveNodeToNewDocument(node, oldDocument, newDocument);
         for (ShadowRoot* shadow = node->youngestShadowRoot(); shadow; shadow = shadow->olderShadowRoot())
             moveTreeToNewDocument(shadow, oldDocument, newDocument);
     }
 }
 
 #ifndef NDEBUG
 static bool didMoveToNewDocumentWasCalled = false;
 static Document* oldDocumentDidMoveToNewDocumentWasCalledWith = 0;
 
 void TreeScopeAdopter::ensureDidMoveToNewDocumentWasCalled(Document* oldDocument)
 {
     ASSERT(!didMoveToNewDocumentWasCalled);
     ASSERT_UNUSED(oldDocument, oldDocument == oldDocumentDidMoveToNewDocumentWasCalledWith);
     didMoveToNewDocumentWasCalled = true;
 }
 #endif
 
+inline void TreeScopeAdopter::updateTreeScope(Node* node) const
+{
+    ASSERT(!node->isTreeScope());
+    ASSERT(node->treeScope() == m_oldScope);
+    m_newScope->guardRef();
+    m_oldScope->guardDeref();
+    node->setTreeScope(m_newScope);
+}
+
 inline void TreeScopeAdopter::moveNodeToNewDocument(Node* node, Document* oldDocument, Document* newDocument) const
 {
     ASSERT(!node->inDocument() || oldDocument != newDocument);
 
     if (node->hasRareData()) {
         NodeRareData* rareData = node->rareData();
         if (rareData->nodeLists())
             rareData->nodeLists()->adoptDocument(oldDocument, newDocument);
     }
 
-    newDocument->guardRef();
     if (oldDocument)
         oldDocument->moveNodeIteratorsToNewDocument(node, newDocument);
 
     if (node->isShadowRoot())
         toShadowRoot(node)->setDocumentScope(newDocument);
 
 #ifndef NDEBUG
     didMoveToNewDocumentWasCalled = false;
     oldDocumentDidMoveToNewDocumentWasCalledWith = oldDocument;
 #endif
 
     node->didMoveToNewDocument(oldDocument);
     ASSERT(didMoveToNewDocumentWasCalled);
-    
-    if (oldDocument)
-        oldDocument->guardDeref();
 }
 
 }