dart:mirrors workaround for generic methods

tests/lib_strong/mirrors/generic_method_test.dart

+// 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 'dart:mirrors';
+import 'package:expect/expect.dart';
+
+class Foo {
+  T bar<T>() => null;
+}
+
+void main() {
+  var type = reflectClass(Foo);
+  Expect.isTrue(type.declarations.keys.contains(#bar));
+}