Revert "Fix fromEnvironment when called from isolates."

tests/corelib/bool_from_environment_default_value_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS 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.
 
-import "dart:isolate";
-
 import "package:expect/expect.dart";
 
-void test(port) {
+main() {
   Expect.isFalse(const bool.fromEnvironment('NOT_FOUND'));
   Expect.isTrue(const bool.fromEnvironment('NOT_FOUND', defaultValue: true));
   Expect.isFalse(const bool.fromEnvironment('NOT_FOUND', defaultValue: false));
   Expect.isNull(const bool.fromEnvironment('NOT_FOUND', defaultValue: null));
-  if (port != null) port.send(null);
 }
-
-main() {
-  test(null);
-  var port = new ReceivePort();
-  Isolate.spawn(test, port.sendPort);
-  port.listen((_) => port.close());
-}