Fix warnings_checker.dart handling of multitests

tests/compiler/dart2js_extra/mirrors_used_warning_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.
 
 @MirrorsUsed(symbols: 'foo')
 import 'dart:mirrors';
 import 'dart:async';
 
 import 'package:expect/expect.dart';
 
 class A {
   noSuchMethod(Invocation invocation) {
     return MirrorSystem.getName(invocation.memberName);
   }
 }
 
 var lines = [];
 capturePrint(Zone self, ZoneDelegate parent, Zone origin, line) {
   lines.add(line);
 }
 
 runTests() {
   // "foo" is in MirrorsUsed and should therefore always work.
   Expect.equals("foo", new A().foo);
   Expect.isTrue(lines.isEmpty);
   var barResult = new A().bar;
-  Expect.equals("bar", barResult); //         /// minif: ok
+  Expect.equals("bar", barResult); //         //# minif: ok
   
   Expect.isTrue(lines.length == 1);
   var line = lines.first;
   Expect.isTrue(line.contains("Warning") &&
-      line.contains("bar") && //              /// minif: continued
+      line.contains("bar") && //              //# minif: continued
       line.contains("minif"));
 }
 
 main() {
   runZoned(runTests,
       zoneSpecification: new ZoneSpecification(print: capturePrint));
 }