Fix warnings_checker.dart handling of multitests

tests/language_strong/sync_generator1_test.dart

Index: tests/language_strong/sync_generator1_test.dart
diff --git a/tests/language_strong/sync_generator1_test.dart b/tests/language_strong/sync_generator1_test.dart
index 6c2b7d701ebc1142551a2b8b80aafafab5546663..9d517e988b8a0ca7ee9f518978d4a1f592ddd843 100644
--- a/tests/language_strong/sync_generator1_test.dart
+++ b/tests/language_strong/sync_generator1_test.dart
@@ -44,7 +44,7 @@ einsZwei() sync* {
 
 dreiVier() sync* {
   // Throws type error: yielded object is not an iterable.
-  yield* 3; /// 01: static type warning
+  yield* 3; //# 01: static type warning
 }
 
 main() {
@@ -80,6 +80,6 @@ main() {
     print(einsZwei());
     Expect.equals("(1, 2, 3, 5, [6])", einsZwei().toString());
 
-    Expect.throws(() => dreiVier().toString()); /// 01: continued
+    Expect.throws(() => dreiVier().toString()); //# 01: continued
   }
 }