- Remove obsolete test.

tests/isolate/package_root_test.dart

-// Copyright (c) 2014, 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:io';
-import 'dart:isolate';
-
-final SPAWN_PACKAGE_ROOT = "file:///no/such/file/";
-
-void main([args, port]) {
-  if (port != null) {
-    testPackageRoot(port);
-    return;
-  }
-  var p = new RawReceivePort();
-  Isolate.spawnUri(Platform.script,
-                   [],
-                   p.sendPort,
-                   packageRoot: Uri.parse(SPAWN_PACKAGE_ROOT));
-  p.handler = (msg) {
-    p.close();
-    if (msg != SPAWN_PACKAGE_ROOT) {
-      throw "Bad package root in child isolate: $msg";
-    }
-  };
-}
-
-testPackageRoot(port) async {
-  var packageRoot = await Isolate.packageRoot;
-  port.send(packageRoot.toString());
-}