Revert "Allowing `e` of any type in `void f(...) => e` in the analyzer."

tests/language/void_arrow_return_test.dart

Index: tests/language/void_arrow_return_test.dart
diff --git a/tests/language/void_arrow_return_test.dart b/tests/language/void_arrow_return_test.dart
deleted file mode 100644
index 0bbcdadc93b3e71fce96edfb4fc2e77c9480dd18..0000000000000000000000000000000000000000
--- a/tests/language/void_arrow_return_test.dart
+++ /dev/null
@@ -1,11 +0,0 @@
-// 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.
-
-// Testing that a void arrow function is allowed to return any type of value.
-
-void foo() => 42;
-
-main() {
-  foo();
-}