Don't expose DocumentWriter to embedding layer

Source/core/fetch/ResourceFetcher.cpp

Index: Source/core/fetch/ResourceFetcher.cpp
diff --git a/Source/core/fetch/ResourceFetcher.cpp b/Source/core/fetch/ResourceFetcher.cpp
index 0c567d4cd05e923593b035dcc3af21cdb059a914..15df4199fca8bb6f7daad13b5dc0b6440c20090e 100644
--- a/Source/core/fetch/ResourceFetcher.cpp
+++ b/Source/core/fetch/ResourceFetcher.cpp
@@ -376,10 +376,12 @@ ResourcePtr<RawResource> ResourceFetcher::fetchMainResource(FetchRequest& reques
 void ResourceFetcher::preCacheSubstituteDataForMainResource(const FetchRequest& request, const SubstituteData& substituteData)
 {
     const KURL& url = request.url();
-    ASSERT(!memoryCache()->resourceForURL(url));
+    if (Resource* oldResource = memoryCache()->resourceForURL(url))
+        memoryCache()->remove(oldResource);
 
     ResourceResponse response(url, substituteData.mimeType(), substituteData.content()->size(), substituteData.textEncoding(), emptyString());
     ResourcePtr<Resource> resource = createResource(Resource::MainResource, request.resourceRequest(), substituteData.textEncoding());
+    resource->setNeedsSynchronousCacheHit(substituteData.forceSynchronousLoad());
     resource->setOptions(request.options());
     resource->setDataBufferingPolicy(BufferData);
     resource->responseReceived(response);