Move some core classes to collection library.

sdk/lib/_internal/compiler/implementation/mirrors/mirrors_util.dart

 // Copyright (c) 2012, 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 mirrors_util;
 
+import 'dart:collection' show Queue;
+
 // TODO(rnystrom): Use "package:" URL (#4968).
 import 'mirrors.dart';
 
 //------------------------------------------------------------------------------
 // Utility functions for using the Mirror API
 //------------------------------------------------------------------------------
 
 /**
  * Returns an iterable over the type declarations directly inheriting from
  * the declaration of this type.
@@ skipping 133 matching lines @@
         //      * Foo
         //      */
         // as "\nFoo\n" and not as "\nFoo\n     ".
         sb.add(line);
       }
     }
     return sb.toString();
   }
   throw new ArgumentError('Invalid comment $comment');
 }