Fix warnings_checker.dart handling of multitests

tests/language/named_parameters_aggregated_test.dart

 // Copyright (c) 2011, 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.
 // Dart test program for testing named parameters.
 
 import "package:expect/expect.dart";
 
 
 class TypeTester<T> {}
 
 // Expect compile-time error as no default values are allowed
 // in closure type definitions.
 typedef void Callback([String msg
- = "" // /// 01: compile-time error
+ = "" // //# 01: compile-time error
  ]);
 
 class NamedParametersAggregatedTests {
 
   static int F31(int a, {int b: 20, int c: 30}) {
     return 100*(100*a + b) + c;
   }
 
   static int f_missing_comma(a
-    [b = 42] /// 02: compile-time error
+    [b = 42] //# 02: compile-time error
     ) => a;
 
   var _handler = null;
 
   // Expect compile-time error as no default values
   // are allowed in closure type.
   void InstallCallback(void cb({String msg
-    : null /// 03: compile-time error
+    : null //# 03: compile-time error
     })) {
     _handler = cb;
   }
 
 }
 
 
 main() {
   // Expect compile-time error due to missing comma in function definition.
   NamedParametersAggregatedTests.f_missing_comma(10
-    , 25 // /// 02: continued
+    , 25 // //# 02: continued
   );
 
   // Expect compile-time erorr due to duplicate named argument.
   NamedParametersAggregatedTests.F31(10, b:25
-    , b:35 //  /// 04: compile-time error
+    , b:35 //  //# 04: compile-time error
   );
 
   // Expect compile-time error due to missing positional argument.
-  Expect.throws(() => NamedParametersAggregatedTests.F31(b:25, c:35), (e) => e is NoSuchMethodError); // /// 05: static type warning
+  Expect.throws(() => NamedParametersAggregatedTests.F31(b:25, c:35), (e) => e is NoSuchMethodError); // //# 05: static type warning
 
   new TypeTester<Callback>();
 
   (new NamedParametersAggregatedTests()).InstallCallback(null);
 
 }