Teach dart_package to understand the packages/ subdirectory

third_party/dart-packages/stack_trace/stack_trace/stack_trace.dart

Index: third_party/dart-packages/stack_trace/stack_trace/stack_trace.dart
diff --git a/third_party/dart-packages/stack_trace/stack_trace/stack_trace.dart b/third_party/dart-packages/stack_trace/stack_trace/stack_trace.dart
deleted file mode 100644
index ac875a9106bbfd3b73154f670e5e66152867fadd..0000000000000000000000000000000000000000
--- a/third_party/dart-packages/stack_trace/stack_trace/stack_trace.dart
+++ /dev/null
@@ -1,28 +0,0 @@
-// Copyright (c) 2013, 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.
-
-/**
- * Stack trace generation and parsing.
- *
- * ## Installing ##
- *
- * Use [pub][] to install this package. Add the following to your `pubspec.yaml`
- * file.
- *
- *     dependencies:
- *       stack_trace: any
- *
- * Then run `pub install`.
- *
- * For more information, see the
- * [stack_trace package on pub.dartlang.org][pkg].
- *
- * [pub]: http://pub.dartlang.org
- * [pkg]: http://pub.dartlang.org/packages/stack_trace
- */
-library stack_trace;
-
-export 'src/trace.dart';
-export 'src/frame.dart';
-export 'src/chain.dart';