Revert "Remaining private libs"

sdk/lib/collection/linked_hash_set.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";
 
 /**
  * A [LinkedHashSet] is a hash-table based [Set] implementation.
  *
  * The `LinkedHashSet` also keep track of the order that elements were inserted
  * in, and iteration happens in first-to-last insertion order.
  *
  * The elements of a `LinkedHashSet` must have consistent [Object.==]
  * and [Object.hashCode] implementations. This means that the `==` operator
  * must define a stable equivalence relation on the elements (reflexive,
@@ skipping 101 matching lines @@
    *
    * The elements are iterated in insertion order.
    */
   void forEach(void action(E element));
 
   /**
    * Provides an iterator that iterates over the elements in insertion order.
    */
   Iterator<E> get iterator;
 }