Add tests for simple packages scenarios

tests/standalone/package/scenarios/packages_file_only/packages_file_only_test.dart

 // Copyright (c) 2015, 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 "package:expect/expect.dart";
+// PackageRoot=none
 
-int count = 0;
+library packages_file_only_test;
 
-void f([void f([x]) = f]) {
-  count++;
-  if (f != null) {
-    f(null);
+import 'package:foo/foo.dart' as foo;
+
+main() {
+  if (foo.bar != 'hello') {
+    throw new Exception('package "foo" was not resolved correctly');
   }
 }
-
-main() {
-  f();
-  Expect.equals(2, count);
-}