Add support for importing using "package:" to the standalone VM.

tests/standalone/src/package/packages/lib3/sub/lib3.dart

Index: tests/standalone/src/package/packages/lib3/sub/lib3.dart
diff --git a/tests/standalone/src/package/packages/lib3/sub/lib3.dart b/tests/standalone/src/package/packages/lib3/sub/lib3.dart
new file mode 100644
index 0000000000000000000000000000000000000000..91a40a031ed200411e899f3f8552bf4a427c9526
--- /dev/null
+++ b/tests/standalone/src/package/packages/lib3/sub/lib3.dart
@@ -0,0 +1,11 @@
+// Copyright (c) 2012, 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.
+
+#library('lib3');
+
+#import('package:shared.dart');
+
+void lib3() {
+  output += '|lib3';
+}