[import] support document.stylesheets in imported documents.

Source/core/dom/StyleSheetCollection.cpp

Index: Source/core/dom/StyleSheetCollection.cpp
diff --git a/Source/core/dom/StyleSheetCollection.cpp b/Source/core/dom/StyleSheetCollection.cpp
index 853a300bbf5f77d90d41fad246f678bfb4cf53e5..c1254fdd0f373f8a0287eaf51e552f7547cb1a1b 100644
--- a/Source/core/dom/StyleSheetCollection.cpp
+++ b/Source/core/dom/StyleSheetCollection.cpp
@@ -53,6 +53,13 @@ void StyleSheetCollectionBase::swap(StyleSheetCollectionBase& other)
     m_activeAuthorStyleSheets.swap(other.m_activeAuthorStyleSheets);
 }
 
+void StyleSheetCollectionBase::swapSheetsForSheetList(Vector<RefPtr<StyleSheet> >& sheets)

[esprehn, 2014/01/24 09:30:10]

We should rename this something like StyleSheetCollection if you plan to create
instances of it. Usually "Base" things have protected constructors and you can't
create them like you did.

+{
+    // 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);
@@ -68,6 +75,12 @@ void StyleSheetCollectionBase::appendSheetForList(StyleSheet* sheet)
     m_styleSheetsForStyleSheetList.append(sheet);
 }
 
+DocumentStyleSheetCollector StyleSheetCollectionBase::collector()

[esprehn, 2014/01/24 09:30:10]

More copying, why not just create the DocumentStyleSheetCollector on the stack?
It's weird to return an object like this by value.

+{
+    return DocumentStyleSheetCollector(m_styleSheetsForStyleSheetList, m_activeAuthorStyleSheets);
+}
+
+
 
 StyleSheetCollection::StyleSheetCollection(TreeScope& treeScope)
     : m_treeScope(treeScope)