Fix warnings_checker.dart handling of multitests

tests/language/regress_22976_test.dart

Index: tests/language/regress_22976_test.dart
diff --git a/tests/language/regress_22976_test.dart b/tests/language/regress_22976_test.dart
index ea29319e8c062d87228ba904170e75c8964822cd..e6e7da612e5c09804a81350b473e98a6617b7ec2 100644
--- a/tests/language/regress_22976_test.dart
+++ b/tests/language/regress_22976_test.dart
@@ -11,6 +11,6 @@ class C<S, T> implements B<S>, A<T> {}
 main() {
   C<int, String> c1 = new C<int, String>();
   C<String, int> c2 = new C<String, int>();
-  A<int> a0 = c1; /// 01: ok
-  A<int> a1 = c2; /// 02: ok
+  A<int> a0 = c1; //# 01: ok
+  A<int> a1 = c2; //# 02: ok
 }