Fix warnings_checker.dart handling of multitests

tests/language/issue_25671b_test.dart

 // Copyright (c) 2016, 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.
 
 import 'package:expect/expect.dart';
 
 class A {
-  noSuchMethod() { //                                   /// 01: static type warning
-    throw new Exception( //                             /// 01: continued
-        "Wrong noSuchMethod() should not be called"); /// 01: continued
-  } //                                                  /// 01: continued
+  noSuchMethod() { //                                   //# 01: static type warning
+    throw new Exception( //                             //# 01: continued
+        "Wrong noSuchMethod() should not be called"); //# 01: continued
+  } //                                                  //# 01: continued
 }
 class C extends Object with A {
   test() {
-    super.v = 1; /// 01: continued
+    super.v = 1; //# 01: continued
   }
 }
 main() {
   C c = new C();
-  Expect.throws(() => c.test(), (e) => e is NoSuchMethodError); /// 01: continued
+  Expect.throws(() => c.test(), (e) => e is NoSuchMethodError); //# 01: continued
 }