Teach dart_package to understand the packages/ subdirectory

third_party/dart-packages/path/BUILD.gn

Index: third_party/dart-packages/path/BUILD.gn
diff --git a/third_party/dart-packages/path/BUILD.gn b/third_party/dart-packages/path/BUILD.gn
deleted file mode 100644
index ce79e928bab3a6398e25f65f6de3582f809ddbe6..0000000000000000000000000000000000000000
--- a/third_party/dart-packages/path/BUILD.gn
+++ /dev/null
@@ -1,21 +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("path") {
-  sources = [
-    "path/path.dart",
-    "path/src/characters.dart",
-    "path/src/context.dart",
-    "path/src/internal_style.dart",
-    "path/src/parsed_path.dart",
-    "path/src/path_exception.dart",
-    "path/src/style.dart",
-    "path/src/utils.dart",
-    "path/src/style/posix.dart",
-    "path/src/style/url.dart",
-    "path/src/style/windows.dart",
-  ]
-}