Fix warnings_checker.dart handling of multitests

tests/lib_strong/mirrors/class_declarations_test.dart

 // Copyright (c) 2013, 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.
 
 library test.declarations_test;
 
 import 'dart:mirrors';
 import 'package:expect/expect.dart';
 
 import 'stringify.dart';
@@ skipping 32 matching lines @@
   Expect.setEquals(
    ['Method(s(_instanceSetter=) in s(Class), private, setter)',
     'Method(s(_staticSetter=) in s(Class), private, static, setter)',
     'Method(s(instanceSetter=) in s(Class), setter)',
     'Method(s(staticSetter=) in s(Class), static, setter)'],
     cm.declarations.values
         .where((dm) => dm is MethodMirror && dm.isSetter).map(stringify),
     'setters');
 
   // dart2js stops testing here.
-  return; // /// 01: ok
+  return; // //# 01: ok
 
   Expect.setEquals(
    ['Method(s(+) in s(Class))',
     'Method(s(_instanceMethod) in s(Class), private)',
     'Method(s(_staticMethod) in s(Class), private, static)',
     'Method(s(abstractMethod) in s(Class), abstract)',
     'Method(s(instanceMethod) in s(Class))',
     'Method(s(staticMethod) in s(Class), static)'],
     cm.declarations.values
         .where((dm) => dm is MethodMirror && dm.isRegularMethod).map(stringify),
@@ skipping 271 matching lines @@
     'Method(s(_mixinStaticGetter) in s(Mixin), private, static, getter)',
     'Method(s(_mixinStaticSetter=) in s(Mixin), private, static, setter)',
     'Method(s(_mixinStaticMethod) in s(Mixin), private, static)'],
     inheritedDeclarations(cm)
         .difference(reflectClass(Object).declarations.values.toSet())
         .map(stringify),
     'transitive less Object');
   // The private members of Object may vary across implementations, so we
   // exclude the declarations of Object in this test case.
 }