Revert "Remaining private libs"

sdk/lib/collection/collections.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.
 
-part of "dart:collection";
+part of "collection.dart";
 
 /**
  * An unmodifiable [List] view of another List.
  *
  * The source of the elements may be a [List] or any [Iterable] with
  * efficient [Iterable.length] and [Iterable.elementAt].
  */
 class UnmodifiableListView<E> extends UnmodifiableListBase<E> {
   final Iterable<E> _source;
 
   /**
    * Creates an unmodifiable list backed by [source].
    *
    * The [source] of the elements may be a [List] or any [Iterable] with
    * efficient [Iterable.length] and [Iterable.elementAt].
    */
   UnmodifiableListView(Iterable<E> source) : _source = source;
   int get length => _source.length;
   E operator [](int index) => _source.elementAt(index);
 }