Move core and coreimpl from corelib/ to lib/core and lib/coreimpl.

corelib/src/set.dart

-// Copyright (c) 2011, 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.
-
-/**
- * This class is the public interface of a set. A set is a collection
- * without duplicates.
- */
-interface Set<E> extends Collection<E>
-    default HashSetImplementation<E extends Hashable> {
-  Set();
-
-  /**
-   * Creates a [Set] that contains all elements of [other].
-   */
-  Set.from(Iterable<E> 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(E value);
-
-  /**
-   * Adds all the elements of the given collection to the set.
-   */
-  void addAll(Collection<E> collection);
-
-  /**
-   * Removes all the elements of the given collection from the set.
-   */
-  void removeAll(Collection<E> collection);
-
-  /**
-   * 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();
-
-}
-
-interface HashSet<E extends Hashable> extends Set<E>
-    default HashSetImplementation<E extends Hashable> {
-  HashSet();
-
-  /**
-   * Creates a [Set] that contains all elements of [other].
-   */
-  HashSet.from(Iterable<E> other);
-}