Ensure that failure to start an isolate all end up in the future.

tests/isolate/isolate_create_error_helper_lib5.dart

 // Copyright (c) 2014, 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.
 
-foo(int arg) {}
+library isolate.create.error_helper5_lib;
 
-class C {
-  C(int arg) {}
-  static foo(int arg) {}
-}
+// This library has a main that is not a function,
+// but is a constant with a function type.
 
-var a;
 
-int get getter => 42;
+void mymain() { print("Not call mymain function!"); }
 
-void set setter(int arg) {
- a = 10;
-}
-
-var list = new List();
-
-var closure = (int arg) => 3;
+const main = mymain;