Implement type variables on local function declarations and expressions.

pkg/front_end/testcases/arrow_function.dart

Index: pkg/front_end/testcases/arrow_function.dart
diff --git a/pkg/front_end/testcases/arrow_function.dart b/pkg/front_end/testcases/arrow_function.dart
new file mode 100644
index 0000000000000000000000000000000000000000..0b8e57d19a7a1fb30ffc02b24dac74189e9fe6d4
--- /dev/null
+++ b/pkg/front_end/testcases/arrow_function.dart
@@ -0,0 +1,5 @@
+// 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.
+
+main<T>() => () => T;