Dart2js, move deferred global vars to the right output unit.

tests/language/deferred_global_test.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.
 
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 
 import "deferred_global_lib.dart" deferred as lib;
 
 void main() {
@@ skipping 22 matching lines @@
     Expect.equals("lazyNonConstGlobal_mutated", lib.readLazyNonConstGlobal());
     Expect.equals(2, lib.sideEffectCounter);
 
     lib.writeLazyConstGlobal("lazyConstGlobal_mutated2");
     lib.writeLazyNonConstGlobal("lazyNonConstGlobal_mutated2");
     Expect.equals("lazyConstGlobal_mutated2", lib.lazyConstGlobal);
     Expect.equals("lazyNonConstGlobal_mutated2", lib.lazyNonConstGlobal);
     Expect.equals("lazyConstGlobal_mutated2", lib.readLazyConstGlobal());
     Expect.equals("lazyNonConstGlobal_mutated2", lib.readLazyNonConstGlobal());
 
+    Expect.mapEquals({}, lib.lazyConstGlobal2);
+
     Expect.equals(2, lib.sideEffectCounter);
     asyncEnd();
   });
 }