Re-add missing pub tests.

sdk/lib/_internal/pub/test/serve/web_socket/url_to_asset_id_errors_test.dart

Index: sdk/lib/_internal/pub/test/serve/web_socket/url_to_asset_id_errors_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/web_socket/url_to_asset_id_errors_test.dart b/sdk/lib/_internal/pub/test/serve/web_socket/url_to_asset_id_errors_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..4fef6a257c9c3745ecf8f2d69daef7be1a58495f
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/serve/web_socket/url_to_asset_id_errors_test.dart
@@ -0,0 +1,36 @@
+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS d.file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library pub_tests;
+
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+import '../utils.dart';
+
+main() {
+  initConfig();
+  setUp(() {
+    d.dir(appPath, [
+      d.appPubspec()
+    ]).create();
+  });
+
+  integration("responds with NOT_SERVED for an unknown domain", () {
+    pubServe();
+    expectWebSocketError("urlToAssetId", {
+      "url": "http://example.com:80/index.html"
+    }, NOT_SERVED, '"example.com:80" is not being served by pub.');
+    endPubServe();
+  });
+
+  integration("responds with NOT_SERVED for an unknown port", () {
+    pubServe();
+    expectWebSocketError("urlToAssetId", {
+      "url": "http://localhost:80/index.html"
+    }, NOT_SERVED, '"localhost:80" is not being served by pub.');
+    endPubServe();
+  });
+}