Fix some tests and exclude others from CRLF rewriting.

pkg/js_ast/test/printer_callback_test.dart

Index: pkg/js_ast/test/printer_callback_test.dart
diff --git a/pkg/js_ast/test/printer_callback_test.dart b/pkg/js_ast/test/printer_callback_test.dart
index 1a1db3590dbcd8c18020bd1bb79ceab277d90b32..b4ff074256cf273ad87d82e8bb522ba705322748 100644
--- a/pkg/js_ast/test/printer_callback_test.dart
+++ b/pkg/js_ast/test/printer_callback_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.
+
 // Test that JS printer callbacks occur when expected.
 
 library js_ast.printer.callback_test;