Fix warnings_checker.dart handling of multitests

tests/language/scope_variable_test.dart

Index: tests/language/scope_variable_test.dart
diff --git a/tests/language/scope_variable_test.dart b/tests/language/scope_variable_test.dart
index 04801ca8852ba137f2b6fd9d1c501d095f693e9a..d731cdf658698e0c506a47cbc37a6ad3cf526491 100644
--- a/tests/language/scope_variable_test.dart
+++ b/tests/language/scope_variable_test.dart
@@ -35,7 +35,7 @@ int testShadowingAfterUse() {
     var c = a;  // Use of 'a' prior to its shadow declaration below.
     var d = b + c;
     // Shadow declaration of 'a'.
-    var a = 5; // /// 01: compile-time error
+    var a = 5; // //# 01: compile-time error
     return d + a;
   }
 }