LibWeb/Fetch: Set HTTP status code on cached responses

This change causes HTTP status codes to be set on cached HTTP responses.

Otherwise, without this change, no status codes at all are set on cached
HTTP responses — which causes all cached responses to default to being
loaded/served with a 200 status code. And as a result of that, if the
cached response is from a 30x redirect, then without this change, when
that cached 30x response is loaded, we don’t follow the redirect —
because we see a 200 status, rather than the expected/original 30x.

Fixes https://github.com/LadybirdBrowser/ladybird/issues/863

Note that this change also reverts the temporary workaround added in
https://github.com/LadybirdBrowser/ladybird/commit/f735c464d3f
(https://github.com/LadybirdBrowser/ladybird/pull/899).

Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp

@@ -1307,6 +1307,7 @@ public:
     ByteBuffer body;
     Infrastructure::Response::BodyInfo body_info;
     ByteBuffer method;
+    Infrastructure::Status status;
     URL::URL url;
     UnixDateTime current_age;
 };
@@ -1347,6 +1348,7 @@ public:
         auto response = Infrastructure::Response::create(realm.vm());
         response->set_body(body);
         response->set_body_info(cached_response.body_info);
+        response->set_status(cached_response.status);
         for (auto& [name, value] : cached_response.headers.headers()) {
             response->header_list()->append(Infrastructure::Header::from_string_pair(name, value));
         }
@@ -1363,6 +1365,7 @@ public:
         cached_response->body = response.body()->source().get<ByteBuffer>();
         cached_response->body_info = response.body_info();
         cached_response->method = MUST(ByteBuffer::copy(http_request.method()));
+        cached_response->status = response.status();
         cached_response->url = http_request.current_url();
         cached_response->current_age = UnixDateTime::now();
         m_cache.set(http_request.current_url(), move(cached_response));
@@ -1459,10 +1462,6 @@ private:
             // FIXME: Implement must-understand cache directive
         }
 
-        // FIXME: This is just for now, ad-hoc — not adhering to any particular spec.
-        if (response.status() == 301 || response.status() == 302 || response.status() == 303 || response.status() == 307 || response.status() == 308)
-            return false;
-
         // - the no-store cache directive is not present in the response (see Section 5.2.2.5);
         if (request.cache_mode() == Infrastructure::Request::CacheMode::NoStore)
             return false;