Starting making dart2js strong mode clean.

tests/compiler/dart2js/analyze_strong_test.dart

Index: tests/compiler/dart2js/analyze_strong_test.dart
diff --git a/tests/compiler/dart2js/analyze_strong_test.dart b/tests/compiler/dart2js/analyze_strong_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..5b5fbd14566e9eb2c98a7b1cbfb10961c06214f4
--- /dev/null
+++ b/tests/compiler/dart2js/analyze_strong_test.dart
@@ -0,0 +1,15 @@
+// Copyright (c) 2017, 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.
+
+import "package:testing/src/run_tests.dart" as testing show main;
+
+main() {
+  // This method is async, but keeps a port open to prevent the VM from exiting
+  // prematurely.
+  return testing.main(<String>[
+    "--config=pkg/compiler/testing_strong.json",
+    "--verbose",
+    "analyze"
+  ]);
+}