Resolve signature from correct scope class (fix #25609).

tests/language/regress_25609_test.dart

Index: tests/language/regress_25609_test.dart
diff --git a/tests/language/export_not_shadowed_by_prefix_helper2.dart b/tests/language/regress_25609_test.dart
similarity index 67%
copy from tests/language/export_not_shadowed_by_prefix_helper2.dart
copy to tests/language/regress_25609_test.dart
index ae2dca5fcf0a4842b29e20d7652b35b6bfd65cfc..579f1c2b34d925c5e6ee74dd1fce9458997bc035 100644
--- a/tests/language/export_not_shadowed_by_prefix_helper2.dart
+++ b/tests/language/regress_25609_test.dart
@@ -2,8 +2,12 @@
 // 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 f() {
-  f_called = true;
-}
+// VMOptions=--error-on-bad-type
+
+import 'regress_25609_lib1.dart';
 
-bool f_called = false;
+Foo baz() => null;
+
+main () {
+  baz();
+}