Fix warnings_checker.dart handling of multitests

tests/compiler/dart2js_extra/minus_zero_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Regression test for issue 17210.
 
 import "package:expect/expect.dart";
 
-const double MINUS_ZERO = -0; /// 01: static type warning, checked mode compile-time error
+const double MINUS_ZERO = -0; //# 01: static type warning, checked mode compile-time error
 
 void main() {
   // Dart2js must not infer that the type-intersection of int and -0.0 is empty.
   // It must get an interceptor for the addition (`i += 3`), or use the native
   // JS + operation.
-  int i = MINUS_ZERO; //  /// 01: continued
-  i += 3; //              /// 01: continued
-  Expect.equals(3, i); // /// 01: continued
+  int i = MINUS_ZERO; //  //# 01: continued
+  i += 3; //              //# 01: continued
+  Expect.equals(3, i); // //# 01: continued
 }