Teach dart_package to understand the packages/ subdirectory

third_party/dart-packages/unittest/BUILD.gn

Index: third_party/dart-packages/unittest/BUILD.gn
diff --git a/third_party/dart-packages/unittest/BUILD.gn b/third_party/dart-packages/unittest/BUILD.gn
deleted file mode 100644
index fbf6abc9fd68a2b5986eb4e653c4daf4e9a8dfa6..0000000000000000000000000000000000000000
--- a/third_party/dart-packages/unittest/BUILD.gn
+++ /dev/null
@@ -1,29 +0,0 @@
-# Copyright 2015 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-import("//mojo/public/dart/rules.gni")
-
-dart_package("unittest") {
-  sources = [
-    "unittest/compact_vm_config.dart",
-    "unittest/html_config.dart",
-    "unittest/html_enhanced_config.dart",
-    "unittest/html_individual_config.dart",
-    "unittest/unittest.dart",
-    "unittest/vm_config.dart",
-    "unittest/src/configuration.dart",
-    "unittest/src/expected_function.dart",
-    "unittest/src/group_context.dart",
-    "unittest/src/internal_test_case.dart",
-    "unittest/src/simple_configuration.dart",
-    "unittest/src/test_case.dart",
-    "unittest/src/test_environment.dart",
-    "unittest/src/utils.dart",
-  ]
-  deps = [
-    "//third_party/dart-packages/matcher",
-    "//third_party/dart-packages/path",
-    "//third_party/dart-packages/stack_trace",
-  ]
-}