delete debug only files from output in release mode

pkg/polymer/test/build/remove_sourcemap_comment_test.dart

+// 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.
+
+library polymer.test.build.remove_sourcemap_comment_test;
+
+import 'package:barback/barback.dart';
+import 'package:polymer/src/build/remove_sourcemap_comment.dart';
+import 'package:unittest/compact_vm_config.dart';
+import 'package:unittest/unittest.dart';
+import 'common.dart';
+
+final phases = [[new RemoveSourcemapComment.asPlugin(
+    new BarbackSettings({}, BarbackMode.RELEASE))]];
+
+void main() {
+  useCompactVMConfiguration();
+
+  testPhases('removes sourcemap comments', phases, {
+      'a|web/test.js': '''
+          var i = 0;
+          //# sourceMappingURL=*.map''',
+  }, {
+      'a|web/test.js': '''
+          var i = 0;''',
+  });
+}