[import] support document.stylesheets in imported documents.

Source/core/dom/StyleSheetCollection.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, 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 35 matching lines @@
 StyleSheetCollectionBase::~StyleSheetCollectionBase()
 {
 }
 
 void StyleSheetCollectionBase::swap(StyleSheetCollectionBase& other)
 {
     m_styleSheetsForStyleSheetList.swap(other.m_styleSheetsForStyleSheetList);
     m_activeAuthorStyleSheets.swap(other.m_activeAuthorStyleSheets);
 }
 
+void StyleSheetCollectionBase::swapSheetsForSheetList(Vector<RefPtr<StyleSheet> >& sheets)
+{
+    // Only called for collection of HTML Imports that never has active sheets.
+    ASSERT(m_activeAuthorStyleSheets.isEmpty());
+    m_styleSheetsForStyleSheetList.swap(sheets);
+}
+
 void StyleSheetCollectionBase::appendActiveStyleSheets(const Vector<RefPtr<CSSStyleSheet> >& sheets)
 {
     m_activeAuthorStyleSheets.append(sheets);
 }
 
 void StyleSheetCollectionBase::appendActiveStyleSheet(CSSStyleSheet* sheet)
 {
     m_activeAuthorStyleSheets.append(sheet);
 }
 
 void StyleSheetCollectionBase::appendSheetForList(StyleSheet* sheet)
 {
     m_styleSheetsForStyleSheetList.append(sheet);
 }
 
-
 StyleSheetCollection::StyleSheetCollection(TreeScope& treeScope)
     : m_treeScope(treeScope)
     , m_hadActiveLoadingStylesheet(false)
     , m_usesRemUnits(false)
 {
 }
 
 void StyleSheetCollection::addStyleSheetCandidateNode(Node* node, bool createdByParser)
 {
     if (!node->inDocument())
@@ skipping 174 matching lines @@
     }
     return false;
 }
 
 void StyleSheetCollection::updateUsesRemUnits()
 {
     m_usesRemUnits = styleSheetsUseRemUnits(m_activeAuthorStyleSheets);
 }
 
 }