- Properly return null if an unknown package is resolved.

tests/isolate/scenarios/short_package/short_package_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.
+
+// PackageRoot=none
+
+import 'dart:io';
+import 'dart:isolate';
+
+import "package:flu";
+
+var PACKAGE_FLU = "package:flu";
+var FLU_TEXT = "flu.text";
+
+testShortResolution(package_uri) async {
+  var fluPackage = await Isolate.resolvePackageUri(Uri.parse(package_uri));
+  print("Resolved $package_uri to $fluPackage");
+  var fluText = fluPackage.resolve(FLU_TEXT);
+  print("Resolved $FLU_TEXT from $package_uri to $fluText");
+  var fluFile = new File.fromUri(fluText);
+  var fluString = await fluFile.readAsString();
+  if (fluString != "Bar") {
+    throw "Contents of $FLU_TEXT not matching.\n"
+          "Got: $fluString\n"
+          "Expected: Bar";
+  }
+}
+
+main([args, port]) async {
+  if (Flu.value != "Flu") {
+    throw "Import of wrong Flu package.";
+  }
+  await testShortResolution(PACKAGE_FLU);
+  await testShortResolution(PACKAGE_FLU + "/");
+  await testShortResolution(PACKAGE_FLU + "/abc.def");
+  print("SUCCESS");
+}