Move synchronously fetching to ResourceFetcher, as well as most of the logic

Source/core/loader/DocumentThreadableLoader.cpp

Index: Source/core/loader/DocumentThreadableLoader.cpp
diff --git a/Source/core/loader/DocumentThreadableLoader.cpp b/Source/core/loader/DocumentThreadableLoader.cpp
index 5c16cec384020ec031867b68165c9a7fe66583d9..77af89e0b6dfe9d6bb929e12c96cdb081b9e9f21 100644
--- a/Source/core/loader/DocumentThreadableLoader.cpp
+++ b/Source/core/loader/DocumentThreadableLoader.cpp
@@ -450,7 +450,7 @@ void DocumentThreadableLoader::loadRequest(const ResourceRequest& request, Secur
             m_client->didFail(error);
             return;
         }
-        identifier = frame->loader()->loadResourceSynchronously(request, m_options.allowCredentials, error, response, data);
+        identifier = m_document->fetcher()->fetchSynchronously(request, m_options.allowCredentials, error, response, data);
     }
 
     InspectorInstrumentation::documentThreadableLoaderStartedLoadingForClient(m_document, identifier, m_client);