Fix warnings_checker.dart handling of multitests

tests/language/type_variable_scope3_test.dart

Index: tests/language/type_variable_scope3_test.dart
diff --git a/tests/language/type_variable_scope3_test.dart b/tests/language/type_variable_scope3_test.dart
index 262131aa08436d3071184887c1da4c6e5f60ea81..99f04d48f8adeeb13eb84fdf3c6c095a53b27258 100644
--- a/tests/language/type_variable_scope3_test.dart
+++ b/tests/language/type_variable_scope3_test.dart
@@ -5,12 +5,12 @@
 // Test that a type parameter cannot be repeated.
 
 class Foo<T
-    , T // /// 00: compile-time error
+    , T // //# 00: compile-time error
     > {
 }
 
 main() {
   new Foo<String
-      , String // /// 00: continued
+      , String // //# 00: continued
       >();
 }