Revert "Re-land "Search for main in the exported names of the main library, not in the library itse…

tests/language/export_ambiguous_main_a.dart

Index: tests/language/export_ambiguous_main_a.dart
diff --git a/tests/language/export_ambiguous_main_a.dart b/tests/language/export_ambiguous_main_a.dart
deleted file mode 100644
index 4a7b820ac658b7a8fa19066d6e4302e69289aa7c..0000000000000000000000000000000000000000
--- a/tests/language/export_ambiguous_main_a.dart
+++ /dev/null
@@ -1,9 +0,0 @@
-// Copyright (c) 2013, 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.
-
-library export_ambiguous_main_a;
-
-main() {
-  print('export_ambiguous_main_a');
-}