Modify scanner and parser to be standalone packages.

pkg/dart_scanner/test/scanner_suite.dart

Index: pkg/dart_scanner/test/scanner_suite.dart
diff --git a/pkg/dart_scanner/test/scanner_suite.dart b/pkg/dart_scanner/test/scanner_suite.dart
new file mode 100644
index 0000000000000000000000000000000000000000..cf9b48e9c15cfef8682b6028870cb420c7d66ce4
--- /dev/null
+++ b/pkg/dart_scanner/test/scanner_suite.dart
@@ -0,0 +1,21 @@
+// Copyright (c) 2016, 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.md file.
+
+import 'package:testing/testing.dart';
+
+import 'package:scanner/testing/scanner_chain.dart';
+
+Future<ChainContext> createContext(
+    Chain suite, Map<String, String> enviroment) async {
+  return new ScannerContext();
+}
+
+class ScannerContext extends ChainContext {
+  final List<Step> steps = const <Step>[
+      const Read(),
+      const Scan(),
+  ];
+}
+
+main(List<String> arguments) => runMe(arguments, createContext);