Ensure correct line endings for method_mirror_source tests.

tests/lib/mirrors/method_mirror_source_test.dart

Index: tests/lib/mirrors/method_mirror_source_test.dart
diff --git a/tests/lib/mirrors/method_mirror_source_test.dart b/tests/lib/mirrors/method_mirror_source_test.dart
index 9b0945209d0c9a22c34a4224d26a8b27db0d2dc1..cea4dc1631840b2542ec3bf3076d99553718b99e 100644
--- a/tests/lib/mirrors/method_mirror_source_test.dart
+++ b/tests/lib/mirrors/method_mirror_source_test.dart
@@ -2,6 +2,8 @@
 // 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.
 
+// Note: This test relies on LF line endings in the source file.
+
 import "dart:mirrors";
 import "package:expect/expect.dart";
 import "method_mirror_source_other.dart";