Fix warnings_checker.dart handling of multitests

tests/language_strong/dynamic_prefix_core_test.dart

Index: tests/language_strong/dynamic_prefix_core_test.dart
diff --git a/tests/language_strong/dynamic_prefix_core_test.dart b/tests/language_strong/dynamic_prefix_core_test.dart
index 610f8e47acb7421361f20d2a9019ed272323a2b8..24bf79a2f6f78ef84bedef15d930098e7d5e6b2f 100644
--- a/tests/language_strong/dynamic_prefix_core_test.dart
+++ b/tests/language_strong/dynamic_prefix_core_test.dart
@@ -11,7 +11,7 @@ void main() {
   // Should still be available because it is not a member of dart:core.
   Expect.isTrue(dynamic is mycore.Type);
 
-  Expect.throws(() => mycore.dynamic is mycore.Type, //    /// 01: static type warning
-                (e) => e is mycore.NoSuchMethodError, //   /// 01: continued
-                'dynamic is not a member of dart:core'); /// 01: continued
+  Expect.throws(() => mycore.dynamic is mycore.Type, //    //# 01: static type warning
+                (e) => e is mycore.NoSuchMethodError, //   //# 01: continued
+                'dynamic is not a member of dart:core'); //# 01: continued
 }