Fix warnings_checker.dart handling of multitests

tests/language/redirecting_factory_malbounded_test.dart

Index: tests/language/redirecting_factory_malbounded_test.dart
diff --git a/tests/language/redirecting_factory_malbounded_test.dart b/tests/language/redirecting_factory_malbounded_test.dart
index 83da0674b6cff57d95854d288dca3dec700c8b6e..90ca684f5812b133fda86fbc9bc3740375b58fd1 100644
--- a/tests/language/redirecting_factory_malbounded_test.dart
+++ b/tests/language/redirecting_factory_malbounded_test.dart
@@ -10,7 +10,7 @@ class Foo<T> extends Bar<T> {
 }
 
 class Bar<T
-            extends num // /// 01: static type warning, dynamic type error
+            extends num // //# 01: static type warning, dynamic type error
                        > {
   factory Bar() {
     return new Foo<T>.create();