Add an extra guard to replaceDocument()

Source/core/dom/DocumentInit.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
@@ skipping 41 matching lines @@
     ~DocumentInit();
 
     const KURL& url() const { return m_url; }
     LocalFrame* frame() const { return m_frame; }
     HTMLImportsController* importsController() const { return m_importsController; }
 
     bool hasSecurityContext() const { return frameForSecurityContext(); }
     bool shouldTreatURLAsSrcdocDocument() const;
     bool shouldSetURL() const;
     bool isSeamlessAllowedFor(Document* child) const;
+    bool shouldReuseDefaultView() const { return m_shouldReuseDefaultView; }
     SandboxFlags sandboxFlags() const;
 
     Document* parent() const { return m_parent.get(); }
     Document* owner() const { return m_owner.get(); }
     KURL parentBaseURL() const;
     LocalFrame* ownerFrame() const;
     Settings* settings() const;
 
     DocumentInit& withRegistrationContext(CustomElementRegistrationContext*);
     DocumentInit& withNewRegistrationContext();
     PassRefPtrWillBeRawPtr<CustomElementRegistrationContext> registrationContext(Document*) const;
     WeakPtrWillBeRawPtr<Document> contextDocument() const;
 
     static DocumentInit fromContext(WeakPtrWillBeRawPtr<Document> contextDocument, const KURL& = KURL());
 
 private:
     LocalFrame* frameForSecurityContext() const;
 
     KURL m_url;
     LocalFrame* m_frame;
     RefPtrWillBeMember<Document> m_parent;
     RefPtrWillBeMember<Document> m_owner;
     WeakPtrWillBeMember<Document> m_contextDocument;
     RawPtrWillBeMember<HTMLImportsController> m_importsController;
     RefPtrWillBeMember<CustomElementRegistrationContext> m_registrationContext;
     bool m_createNewRegistrationContext;
+
+    // In some rare cases, we'll re-use a LocalDOMWindow for a new Document. For example,
+    // when a script calls window.open("..."), the browser gives JavaScript a window
+    // synchronously but kicks off the load in the window asynchronously. Web sites
+    // expect that modifications that they make to the window object synchronously
+    // won't be blown away when the network load commits. To make that happen, we
+    // "securely transition" the existing LocalDOMWindow to the Document that results from
+    // the network load. See also SecurityContext::isSecureTransitionTo.
+    // FIXME: This is for DocumentWriter creation, not for one of Document.
+    bool m_shouldReuseDefaultView;
 };
 
 } // namespace blink
 
 #endif // DocumentInit_h