Remove dead code for an unused (old) task

pkg/analyzer/test/task/test_all.dart

Index: pkg/analyzer/test/task/test_all.dart
diff --git a/pkg/analyzer/test/task/test_all.dart b/pkg/analyzer/test/task/test_all.dart
deleted file mode 100644
index 9ecd16215ffb783037abdb763a392bfa04311251..0000000000000000000000000000000000000000
--- a/pkg/analyzer/test/task/test_all.dart
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright (c) 2014, 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 test.task;
-
-import 'package:unittest/unittest.dart';
-
-import 'task_dart_test.dart' as task_dart_test;
-
-/// Utility for manually running all tests.
-main() {
-  groupSep = ' | ';
-  group('generated tests', () {
-    task_dart_test.main();
-  });
-}