- Allow specifying of package: URIs for packageConfig and packageRoot when

tests/isolate/scenarios/package_relative_root/package_relative_root_test.dart

-// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
+// PackageRoot=none
+
 import 'dart:io';
 import 'dart:isolate';
 
-final PACKAGE_URI = "package:foo/bar.dart";
-final PACKAGE_PATH = "file:///no/such/directory/bar.dart";
+import "package:foo/foo.dart";
+import "package:bar/bar.dart";
+
+var CONFIG_URI = "package:bar/spawned_packages/";
 
 main([args, port]) async {
   if (port != null) {
-    testPackageResolution(port);
+    testCorrectBarPackage(port);
     return;
   }
   var p = new RawReceivePort();
   Isolate.spawnUri(Platform.script,
                    [],
                    p.sendPort,
-                   automaticPackageResolution: true);
+                   packageRoot: Uri.parse(CONFIG_URI));
   p.handler = (msg) {
     p.close();
     if (msg is! List) {
       print(msg.runtimeType);
       throw "Failure return from spawned isolate:\n\n$msg";
     }
-    var child_pkg_config = Platform.script.resolve(".packages");
-    if (msg[0] != child_pkg_config.toString()) {
+    if (msg[0] != "Foo") {
       throw "Bad package config in child isolate: ${msg[0]}\n"
-            "Expected: $child_pkg_config";
+            "Expected: 'Foo'";
     }
-    if (msg[1] != PACKAGE_PATH) {
-      throw "Package path not matching: ${msg[1]}";
+    if (msg[1] != "Bar2") {
+      throw "Package path not matching: ${msg[1]}\n"
+            "Expected: 'Bar2'";
     }
     print("SUCCESS");
   };
-  print("Spawning isolate's package root: ${await Isolate.packageRoot}");
+  if (Bar.value != "Bar1") {
+    throw "Spawning isolate package:bar invalid.";
+  }
+  print("Spawned isolate resolved $CONFIG_URI to: "
+        "${await Isolate.resolvePackageUri(Uri.parse(CONFIG_URI))}");
 }
 
-testPackageResolution(port) async {
+testCorrectBarPackage(port) async {
   try {
     var packageRootStr = Platform.packageRoot;
     var packageConfigStr = Platform.packageConfig;
     var packageConfig = await Isolate.packageConfig;
-    var resolvedPkg = await Isolate.resolvePackageUri(Uri.parse(PACKAGE_URI));
+    var resolvedPkg = await Isolate.resolvePackageUri(Uri.parse(CONFIG_URI));
     print("Spawned isolate's package root flag: $packageRootStr");
     print("Spawned isolate's package config flag: $packageConfigStr");
     print("Spawned isolate's loaded package config: $packageConfig");
     print("Spawned isolate's resolved package path: $resolvedPkg");
-    port.send([packageConfig?.toString(), resolvedPkg?.toString()]);
+    port.send([Foo.value, Bar.value]);
   } catch (e, s) {
     port.send("$e\n$s\n");
   }
 }