Emphasize that the XSS tests should not be casually suppressed

tests/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart

Index: tests/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart
diff --git a/tests/html/node_validator_test.dart b/tests/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart
similarity index 98%
rename from tests/html/node_validator_test.dart
rename to tests/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart
index 46b2bebacce7352d0fbbc40121b74ccde8bf6b59..cb0196d7393693b2d0fa3f8ce35dc06b31ca91a2 100644
--- a/tests/html/node_validator_test.dart
+++ b/tests/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart
@@ -2,7 +2,11 @@
 // 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 validator_test;
+/// This tests HTML validation and sanitization, which is very important
+/// for prevent XSS or other attacks. If you suppress this, or parts of it
+/// please make it a critical bug and bring it to the attention of the
+/// dart:html maintainers.
+library node_validator_test;
 
 import 'dart:html';
 import 'dart:svg' as svg;