Move renderFallbackContent() into FrameOwner interface.

Source/core/loader/DocumentLoader.cpp

Index: Source/core/loader/DocumentLoader.cpp
diff --git a/Source/core/loader/DocumentLoader.cpp b/Source/core/loader/DocumentLoader.cpp
index 6ab92c1d28ed752fea7653f45cd80fca278dc4b5..ca5e3aa5b68acf618e8c7415722a219476f384ce 100644
--- a/Source/core/loader/DocumentLoader.cpp
+++ b/Source/core/loader/DocumentLoader.cpp
@@ -458,14 +458,10 @@ void DocumentLoader::responseReceived(Resource* resource, const ResourceResponse
 
     if (m_response.isHTTP()) {
         int status = m_response.httpStatusCode();
-        // FIXME: Fallback content only works if the parent is in the same processs.
         if ((status < 200 || status >= 300) && m_frame->owner()) {
-            if (!m_frame->deprecatedLocalOwner()) {
-                ASSERT_NOT_REACHED();
-            } else if (m_frame->deprecatedLocalOwner()->isObjectElement()) {
-                m_frame->deprecatedLocalOwner()->renderFallbackContent();
-                // object elements are no longer rendered after we fallback, so don't
-                // keep trying to process data from their load
+            if (m_frame->owner()->renderFallbackContent()) {
+                // Don't keep trying to process the data from the load if the
+                // fallback content replaces the frame.
                 cancelMainResourceLoad(ResourceError::cancelledError(m_request.url()));
             }
         }