Fix warnings_checker.dart handling of multitests

tests/language_strong/substring_test.dart

Index: tests/language_strong/substring_test.dart
diff --git a/tests/language_strong/substring_test.dart b/tests/language_strong/substring_test.dart
index e2dc3f1712a8d23345085d39dd44c8996c1e2c52..ccc92f6ffd59138aad00bbe4870e79cd35569e89 100644
--- a/tests/language_strong/substring_test.dart
+++ b/tests/language_strong/substring_test.dart
@@ -8,8 +8,8 @@ import "package:expect/expect.dart";
 
 main() {
   try {
-    print("abcdef".substring(1.5, 3.5)); //   /// 01: static type warning
-    Expect.fail("Should have thrown an exception"); // /// 01: continued
+    print("abcdef".substring(1.5, 3.5)); //   //# 01: static type warning
+    Expect.fail("Should have thrown an exception"); // //# 01: continued
   } on TypeError catch (e) {
     // OK.
   } on ArgumentError catch (e) {