Fix a corner case of block closure inference.

pkg/front_end/testcases/inference/inferred_type_block_closure_no_args_no_return_void_context.dart.strong.expect

Index: pkg/front_end/testcases/inference/inferred_type_block_closure_no_args_no_return_void_context.dart.strong.expect
diff --git a/pkg/front_end/testcases/inference/inferred_type_block_closure_no_args_no_return_void_context.dart.strong.expect b/pkg/front_end/testcases/inference/inferred_type_block_closure_no_args_no_return_void_context.dart.strong.expect
new file mode 100644
index 0000000000000000000000000000000000000000..8b9f2be91c970d6e72ee0a8c0c242ed64867149c
--- /dev/null
+++ b/pkg/front_end/testcases/inference/inferred_type_block_closure_no_args_no_return_void_context.dart.strong.expect
@@ -0,0 +1,11 @@
+library test;
+import self as self;
+import "dart:core" as core;
+
+class C extends core::Object {
+  constructor •(() → void func) → void
+    : super core::Object::•() {}
+}
+static method main() → dynamic {
+  self::C c = new self::C::•(() → core::Null {});
+}