Search for main in the exported names of the main library, not in the library itself.

tests/language/export_main_test.dart

Index: tests/language/export_main_test.dart
diff --git a/tests/compiler/dart2js_extra/12_test.dart b/tests/language/export_main_test.dart
similarity index 85%
copy from tests/compiler/dart2js_extra/12_test.dart
copy to tests/language/export_main_test.dart
index 80a758a5da39e700a7aa086b99d3dc1089431737..9f9bb597e9d3a5a94e03a0df2a2b4a46db9e7c71 100644
--- a/tests/compiler/dart2js_extra/12_test.dart
+++ b/tests/language/export_main_test.dart
@@ -2,6 +2,4 @@
 // 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.
 
-void main() {
-  print(3 + 4 + 5);
-}
+export 'top_level_entry_test.dart';