Rationalize arg handling for pub build and serve.

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

Index: sdk/lib/_internal/pub/test/serve/roots/throws_an_error_by_default_if_web_and_test_dont_exist_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/roots/throws_an_error_by_default_if_web_and_test_dont_exist_test.dart b/sdk/lib/_internal/pub/test/serve/roots/throws_an_error_by_default_if_web_and_test_dont_exist_test.dart
deleted file mode 100644
index dfea16b22d71ced87695cdb37426286d3acd45ca..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/pub/test/serve/roots/throws_an_error_by_default_if_web_and_test_dont_exist_test.dart
+++ /dev/null
@@ -1,26 +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 by default if web and test don't exist", () {
-    d.dir(appPath, [
-      d.appPubspec()
-    ]).create();
-
-    var server = startPubServe(createWebDir: false);
-    server.stderr.expect(emitsLines(
-        'Your package must have "web" and/or "test" directories to serve,\n'
-        'or you must pass in directories to serve explicitly.'));
-    server.shouldExit(exit_codes.USAGE);
-  });
-}