Fix warnings_checker.dart handling of multitests

tests/language_strong/const_factory_with_body_test.dart

Index: tests/language_strong/const_factory_with_body_test.dart
diff --git a/tests/language_strong/const_factory_with_body_test.dart b/tests/language_strong/const_factory_with_body_test.dart
index dea62482ad5276c9d7d6749f7388ac6d6a24b35b..1c6a74e1257644219547c027176fd10adc286fc3 100644
--- a/tests/language_strong/const_factory_with_body_test.dart
+++ b/tests/language_strong/const_factory_with_body_test.dart
@@ -5,9 +5,9 @@
 // Tests that a "const factory" with body produces a compile-time error.
 
 class ConstFactoryWithBody {
-  const factory ConstFactoryWithBody.one() { } // /// 01: compile-time error
+  const factory ConstFactoryWithBody.one() { } // //# 01: compile-time error
 }
 
 main() {
-  const ConstFactoryWithBody.one(); // /// 01: continued
+  const ConstFactoryWithBody.one(); // //# 01: continued
 }