HTML Imports: Teach preloader about HTML Imports.

Source/core/loader/DocumentLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 127 matching lines @@
     return m_request;
 }
 
 const KURL& DocumentLoader::url() const
 {
     return m_request.url();
 }
 
 void DocumentLoader::startPreload(Resource::Type type, FetchRequest& request)
 {
-    ASSERT(type == Resource::Script || type == Resource::CSSStyleSheet || type == Resource::Image);
+    ASSERT(type == Resource::Script || type == Resource::CSSStyleSheet || type == Resource::Image || type == Resource::ImportResource);
     ResourcePtr<Resource> resource;
-    if (type == Resource::Image)
+    switch (type) {
+    case Resource::Image:
         resource = ImageResource::fetch(request, fetcher());
-    else if (type == Resource::Script)
+        break;
+    case Resource::Script:
         resource = ScriptResource::fetch(request, fetcher());
-    else
+        break;
+    case Resource::CSSStyleSheet:
         resource = CSSStyleSheetResource::fetch(request, fetcher());
+        break;
+    default: // Resource::ImportResource
+        resource = RawResource::fetchImport(request, fetcher());
+        break;
+    }
 
     if (resource)
         fetcher()->preloadStarted(resource.get());
 }
 
 void DocumentLoader::updateForSameDocumentNavigation(const KURL& newURL, SameDocumentNavigationSource sameDocumentNavigationSource)
 {
     KURL oldURL = m_request.url();
     m_originalRequest.setURL(newURL);
     m_request.setURL(newURL);
@@ skipping 625 matching lines @@
 // This is only called by FrameLoader::replaceDocumentWhileExecutingJavaScriptURL()
 void DocumentLoader::replaceDocumentWhileExecutingJavaScriptURL(const DocumentInit& init, const String& source, Document* ownerDocument)
 {
     m_writer = createWriterFor(ownerDocument, init, mimeType(), m_writer ? m_writer->encoding() : emptyAtom, true, ForceSynchronousParsing);
     if (!source.isNull())
         m_writer->appendReplacingData(source);
     endWriting(m_writer.get());
 }
 
 } // namespace blink