Fix warnings_checker.dart handling of multitests

tests/language_strong/duplicate_implements_test.dart

Index: tests/language_strong/duplicate_implements_test.dart
diff --git a/tests/language_strong/duplicate_implements_test.dart b/tests/language_strong/duplicate_implements_test.dart
index c85e40c98fb3453bf9015c4efedd52a0154e86e4..8bb74e3a0d09154b82b7fdbf4562cb355c19a623 100644
--- a/tests/language_strong/duplicate_implements_test.dart
+++ b/tests/language_strong/duplicate_implements_test.dart
@@ -8,15 +8,15 @@ abstract class I { }
 abstract class J { }
 abstract class K<T> { }
 
-class X implements I, J, I { } //              /// 01: compile-time error
-class X implements J, I, K<int>, K<int> { } // /// 02: compile-time error
+class X implements I, J, I { } //              //# 01: compile-time error
+class X implements J, I, K<int>, K<int> { } // //# 02: compile-time error
 
-abstract class Z implements I, J, J { } //             /// 03: compile-time error
-abstract class Z implements K<int>, K<int> { } //      /// 04: compile-time error
+abstract class Z implements I, J, J { } //             //# 03: compile-time error
+abstract class Z implements K<int>, K<int> { } //      //# 04: compile-time error
 
 main() {
-  X x = new X(); // /// 01: continued
-  X x = new X(); // /// 02: continued
-  Z z = new Z(); // /// 03: continued
-  Z z = new Z(); // /// 04: continued
+  X x = new X(); // //# 01: continued
+  X x = new X(); // //# 02: continued
+  Z z = new Z(); // //# 03: continued
+  Z z = new Z(); // //# 04: continued
 }