Revert "Switch libraries to using new tags."

sdk/lib/core/sequences.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.
 
-part of dart.core;
-
 /**
  * An indexed sequence of elements of the same type.
  *
  * This is a primitive interface that any finite integer-indexable
  * sequence can implement.
  * It is intended for data structures where access by index is
  * the most efficient way to access the data.
  */
 abstract class Sequence<E> {
   /**
@@ skipping 181 matching lines @@
   Sequence<E> _sequence;
   int _position;
   SequenceIterator(this._sequence) : _position = 0;
   bool get hasNext => _position < _sequence.length;
   E next() {
     if (hasNext) return _sequence[_position++];
     throw new StateError("No more elements");
   }
 }