Move some core classes to collection library.

sdk/lib/collection/set.dart

Index: sdk/lib/collection/set.dart
diff --git a/sdk/lib/core/set.dart b/sdk/lib/collection/set.dart
similarity index 64%
copy from sdk/lib/core/set.dart
copy to sdk/lib/collection/set.dart
index 556c1fa12539554eb10f32590043a4359293ac88..9363676e867eccee06f9a299397fb50a0c97806d 100644
--- a/sdk/lib/core/set.dart
+++ b/sdk/lib/collection/set.dart
@@ -1,62 +1,9 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.core;
+part of dart.collection;
 
-/**
- * This class is the public interface of a set. A set is a collection
- * without duplicates.
- */
-abstract class Set<E> extends Collection<E> {
-  factory Set() => new HashSet<E>();
-
-  /**
-   * Creates a [Set] that contains all elements of [other].
-   */
-  factory Set.from(Iterable<E> other) => new HashSet<E>.from(other);
-
-  /**
-   * Returns true if [value] is in the set.
-   */
-  bool contains(E value);
-
-  /**
-   * Adds [value] into the set. The method has no effect if
-   * [value] was already in the set.
-   */
-  void add(E value);
-
-  /**
-   * Removes [value] from the set. Returns true if [value] was
-   * in the set. Returns false otherwise. The method has no effect
-   * if [value] value was not in the set.
-   */
-  bool remove(Object value);
-
-  /**
-   * Returns true if [collection] contains all the elements of this
-   * collection.
-   */
-  bool isSubsetOf(Collection<E> collection);
-
-  /**
-   * Returns true if this collection contains all the elements of
-   * [collection].
-   */
-  bool containsAll(Collection<E> collection);
-
-  /**
-   * Returns a new set which is the intersection between this set and
-   * the given collection.
-   */
-  Set<E> intersection(Collection<E> other);
-
-  /**
-   * Removes all elements in the set.
-   */
-  void clear();
-}
 
 
 class HashSet<E> extends Collection<E> implements Set<E> {