Rationalize arg handling for pub build and serve.

sdk/lib/_internal/pub/test/serve/roots/throws_an_error_if_custom_roots_dont_exist_test.dart

Index: sdk/lib/_internal/pub/test/serve/roots/throws_an_error_if_custom_roots_dont_exist_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/roots/throws_an_error_if_custom_roots_dont_exist_test.dart b/sdk/lib/_internal/pub/test/serve/roots/throws_an_error_if_custom_roots_dont_exist_test.dart
deleted file mode 100644
index fac152f128a5f7a32b9fa674a232b960b5424baf..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/pub/test/serve/roots/throws_an_error_if_custom_roots_dont_exist_test.dart
+++ /dev/null
@@ -1,25 +0,0 @@
-// 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 '../../../lib/src/exit_codes.dart' as exit_codes;
-
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-import '../utils.dart';
-
-main() {
-  initConfig();
-  integration("throws an error if custom roots don't exist", () {
-    d.dir(appPath, [
-      d.appPubspec(),
-      d.dir("baz")
-    ]).create();
-
-    var server = startPubServe(args: ["foo", "bar", "baz"]);
-    server.stderr.expect('Directories "bar" and "foo" don\'t exist.');
-    server.shouldExit(exit_codes.USAGE);
-  });
-}