Fix for issue 26555, do not inherit package root and package config from the parent isolate when do…

tests/standalone/packages_file_test.dart

 // Copyright (c) 2016, 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:async";
 import "dart:io";
 import "dart:convert" show JSON;
 import "package:path/path.dart" as p;
 import "package:async_helper/async_helper.dart";
 
@@ skipping 67 matching lines @@
   }
 
   asyncEnd();
 }
 
 /// Test running the test of the configuration through [Isolate.spawn].
 ///
 /// This should not change the expected results compared to running it
 /// directly.
 Configuration spawn(Configuration conf) {
-  // TODO(26555): Clean up when fixed.
-  // TEMPORARY FIX FOR ISSUE #26555 (http://dartbug.com/26555)
-  if (conf.expect["iroot"] == null &&
-      conf.expect["iconf"] == null &&
-      conf.expect["pconf"] != null) {
-    // The spawned isolate will do a search for a package file or root,
-    // which is not what the original did. Skip test for now.
-    return null;
-  }
-  // REMOVE WHEN ISSUE FIXED!
   return conf.update(
     description: conf.description + "/spawn",
     main: "spawnMain",
     newArgs: [conf.mainType],
-    // TEMPORARY FIX FOR ISSUE #26555 (http://dartbug.com/26555)
-    expect: {
-      "proot": conf.expect["iroot"],
-      "pconf": conf.expect["iconf"],
-    }
-    // REMOVE WHEN ISSUE FIXED!
+    expect: null
   );
 }
 
 /// Tests running a spawnUri on top of the configuration before testing.
 ///
 /// The `spawnUri` call has no explicit root or config parameter, and
 /// shouldn't search for one, so it implicitly inherits the current isolate's
 /// actual root or configuration.
 Configuration spawnUriInherit(Configuration conf) {
   if (conf.expect["iroot"] == null &&
@@ skipping 874 matching lines @@
 void insertFileAt(Map file, Map http,
                   String path, String name, String content) {
   var parts = path.split('/').toList();
   var dir = (parts[0] == "%file") ? file : http;
   for (var i = 1; i < parts.length - 1; i++) {
     var entry = parts[i];
     dir = dir[entry] ?? (dir[entry] = {});
   }
   dir[name] = content;
 }