[HTML Imports] Implement sub-imports processing.

Source/core/dom/Document.cpp

 /*
  * 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, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 838 matching lines @@
 
 CustomElementRegistry* Document::ensureCustomElementRegistry()
 {
     if (!m_registry) {
         ASSERT(isHTMLDocument() || isXHTMLDocument());
         m_registry = adoptRef(new CustomElementRegistry(this));
     }
     return m_registry.get();
 }
 
-HTMLImportsController* Document::ensureImports()
+void Document::setImports(PassRefPtr<HTMLImportsController> imports)
 {
-    if (!m_imports)
-        m_imports = HTMLImportsController::create(this);
-    return m_imports.get();
+    ASSERT(!m_imports);
+    m_imports = imports;
 }
 
 void Document::didLoadAllImports()
 {
     executeScriptsWaitingForResourcesIfNeeded();
 }
 
 bool Document::haveImportsLoaded() const
 {
     return !m_imports || m_imports->haveLoaded();
@@ skipping 4357 matching lines @@
 {
     return DocumentLifecycleNotifier::create(this);
 }
 
 DocumentLifecycleNotifier* Document::lifecycleNotifier()
 {
     return static_cast<DocumentLifecycleNotifier*>(ScriptExecutionContext::lifecycleNotifier());
 }
 
 } // namespace WebCore