Improve parallelism when loading transformer plugins.

sdk/lib/_internal/pub/test/transformer/detects_a_transformer_cycle_test.dart

Index: sdk/lib/_internal/pub/test/transformer/detects_a_transformer_cycle_test.dart
diff --git a/sdk/lib/_internal/pub/test/transformer/detects_a_transformer_cycle_test.dart b/sdk/lib/_internal/pub/test/transformer/detects_a_transformer_cycle_test.dart
deleted file mode 100644
index df8c0baabb2443f70f0235f3748f0b46f984c40c..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/pub/test/transformer/detects_a_transformer_cycle_test.dart
+++ /dev/null
@@ -1,48 +0,0 @@
-// Copyright (c) 2013, 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 '../descriptor.dart' as d;
-import '../test_pub.dart';
-import '../serve/utils.dart';
-
-main() {
-  initConfig();
-  withBarbackVersions("any", () {
-    integration("detects a transformer cycle", () {
-      d.dir("foo", [
-        d.pubspec({
-          "name": "foo",
-          "version": "1.0.0",
-          "transformers": ["myapp/transformer"],
-          "dependencies": {'myapp': {'path': '../myapp'}}
-        }),
-        d.dir("lib", [
-          d.file("transformer.dart", dartTransformer('foo')),
-        ])
-      ]).create();
-
-      d.dir(appPath, [
-        d.pubspec({
-          "name": "myapp",
-          "transformers": ["foo/transformer"],
-          "dependencies": {'foo': {'path': '../foo'}}
-        }),
-        d.dir("lib", [
-          d.file("transformer.dart", dartTransformer('myapp')),
-        ])
-      ]).create();
-
-      createLockFile('myapp', sandbox: ['foo'], pkg: ['barback']);
-
-      var process = startPubServe();
-      process.shouldExit(1);
-      process.stderr.expect(emitsLines(
-          "Transformer cycle detected:\n"
-          "  foo is transformed by myapp/transformer\n"
-          "  myapp is transformed by foo/transformer"));
-    });
-  });
-}