Fix warnings_checker.dart handling of multitests

tests/corelib_strong/string_trimlr_test.dart

Index: tests/corelib_strong/string_trimlr_test.dart
diff --git a/tests/corelib_strong/string_trimlr_test.dart b/tests/corelib_strong/string_trimlr_test.dart
index 67276fda53206f82ca77c08976fedc74dea65c81..bada40e9a9c21ddf49ae998fc41742ccea24197d 100644
--- a/tests/corelib_strong/string_trimlr_test.dart
+++ b/tests/corelib_strong/string_trimlr_test.dart
@@ -92,7 +92,7 @@ main() {
     // This line makes string_trimlr_test/none fail but /01 succeede where
     // this bug is in the JS. Both succeede on the VM and where the bug is
     // not. Remove this line and comment if all JS engines fix it.
-    if (i == 0x200b) continue; //             /// 01: ok
+    if (i == 0x200b) continue; //             //# 01: ok
 
     var s = new String.fromCharCode(i);
     Expect.identical(s, s.trimLeft());