Refactoring: Introduce HTMLImport interface to form import tree.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 4282042f7853697cb2c5e9395eff38e1263c3fa7..e8a6914561be276b2be5f79ead029e8fc85c596d 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -105,7 +105,7 @@
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/html/HTMLHeadElement.h"
 #include "core/html/HTMLIFrameElement.h"
-#include "core/html/HTMLImportsController.h"
+#include "core/html/HTMLImport.h"
 #include "core/html/HTMLLinkElement.h"
 #include "core/html/HTMLNameCollection.h"
 #include "core/html/HTMLScriptElement.h"
@@ -441,6 +441,7 @@ Document::Document(Frame* frame, const KURL& url, DocumentClassFlags documentCla
     , m_prerenderer(Prerenderer::create(this))
     , m_textAutosizer(TextAutosizer::create(this))
     , m_pendingTasksTimer(this, &Document::pendingTasksTimerFired)
+    , m_imports(0)
     , m_scheduledTasksAreSuspended(false)
     , m_sharedObjectPoolClearTimer(this, &Document::sharedObjectPoolClearTimerFired)
 #ifndef NDEBUG
@@ -585,7 +586,7 @@ void Document::dispose()
     detachParser();
 
     m_registry.clear();
-    m_imports.clear();
+    m_imports = 0;
 
     // removeDetachedChildren() doesn't always unregister IDs,
     // so tear down scope information upfront to avoid having stale references in the map.
@@ -769,9 +770,9 @@ CustomElementRegistry* Document::ensureCustomElementRegistry()
     return m_registry.get();
 }
 
-void Document::setImports(PassRefPtr<HTMLImportsController> imports)
+void Document::setImports(HTMLImport* imports)
 {
-    ASSERT(!m_imports);
+    ASSERT(!m_imports || !imports);
     m_imports = imports;
 }
 
@@ -782,7 +783,7 @@ void Document::didLoadAllImports()
 
 bool Document::haveImportsLoaded() const
 {
-    return !m_imports || m_imports->haveLoaded();
+    return !m_imports || m_imports->haveChildrenLoaded();
 }
 
 PassRefPtr<DocumentFragment> Document::createDocumentFragment()