Fix a corner case of block closure inference.

pkg/front_end/testcases/inference/inferred_type_block_closure_no_args_no_return_void_context.dart

Index: pkg/front_end/testcases/inference/inferred_type_block_closure_no_args_no_return_void_context.dart
diff --git a/pkg/front_end/testcases/inference/inferred_type_block_closure_no_args_no_return_void_context.dart b/pkg/front_end/testcases/inference/inferred_type_block_closure_no_args_no_return_void_context.dart
new file mode 100644
index 0000000000000000000000000000000000000000..51cc0a96f876e01bb9a9d773f823c781c3c2eaf8
--- /dev/null
+++ b/pkg/front_end/testcases/inference/inferred_type_block_closure_no_args_no_return_void_context.dart
@@ -0,0 +1,14 @@
+// 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.
+
+/*@testedFeatures=inference*/
+library test;
+
+class C {
+  C(void func()) {}
+}
+
+main() {
+  var /*@type=C*/ c = new C(/*@returnType=Null*/ () {});
+}