remove generated_sdk from checked in code

test/generated_sdk/lib/collection/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;
-
-/** Common parts of [HashSet] and [LinkedHashSet] implementations. */
-abstract class _HashSetBase<E> extends SetBase<E> {
-
-  // The following two methods override the ones in SetBase.
-  // It's possible to be more efficient if we have a way to create an empty
-  // set of the correct type.
-
-  Set<E> difference(Set<Object> other) {
-    Set<E> result = _newSet();
-    for (var element in this) {
-      if (!other.contains(element)) result.add(element);
-    }
-    return result;
-  }
-
-  Set<E> intersection(Set<Object> other) {
-    Set<E> result = _newSet();
-    for (var element in this) {
-      if (other.contains(element)) result.add(element);
-    }
-    return result;
-  }
-
-  Set<E> _newSet();
-
-  // Subclasses can optimize this further.
-  Set<E> toSet() => _newSet()..addAll(this);
-}
-
-/**
- * An unordered hash-table based [Set] implementation.
- *
- * The elements of a `HashSet` must have consistent equality
- * and hashCode implementations. This means that the equals operation
- * must define a stable equivalence relation on the elements (reflexive,
- * symmetric, transitive, and consistent over time), and that the hashCode
- * must consistent with equality, so that the same for objects that are
- * considered equal.
- *
- * The set allows `null` as an element.
- *
- * Most simple operations on `HashSet` are done in (potentially amorteized)
- * constant time: [add], [contains], [remove], and [length], provided the hash
- * codes of objects are well distributed.
- */
-abstract class HashSet<E> implements Set<E> {
-  /**
-   * Create a hash set using the provided [equals] as equality.
-   *
-   * The provided [equals] must define a stable equivalence relation, and
-   * [hashCode] must be consistent with [equals]. If the [equals] or [hashCode]
-   * methods won't work on all objects, but only to instances of E, the
-   * [isValidKey] predicate can be used to restrict the keys that they are
-   * applied to. Any key for which [isValidKey] returns false is automatically
-   * assumed to not be in the set.
-   *
-   * If [equals] or [hashCode] are omitted, the set uses
-   * the objects' intrinsic [Object.operator==] and [Object.hashCode].
-   *
-   * If [isValidKey] is omitted, it defaults to testing if the object is an
-   * [E] instance.
-   *
-   * If you supply one of [equals] and [hashCode],
-   * you should generally also to supply the other.
-   * An example would be using [identical] and [identityHashCode],
-   * which is equivalent to using the shorthand [LinkedSet.identity]).
-   */
-  factory HashSet({ bool equals(E e1, E e2),
-                    int hashCode(E e),
-                    bool isValidKey(Object potentialKey) }) {
-    if (isValidKey == null) {
-      if (hashCode == null) {
-        if (equals == null) {
-          return new _HashSet<E>();
-        }
-        hashCode = _defaultHashCode;
-      } else {
-        if (identical(identityHashCode, hashCode) &&
-            identical(identical, equals)) {
-          return new _IdentityHashSet<E>();
-        }
-        if (equals == null) {
-          equals = _defaultEquals;
-        }
-      }
-    } else {
-      if (hashCode == null) {
-        hashCode = _defaultHashCode;
-      }
-      if (equals == null) {
-        equals = _defaultEquals;
-      }
-    }
-    return new _CustomHashSet<E>(equals, hashCode, isValidKey);
-  }
-
-  /**
-   * Creates an unordered identity-based set.
-   *
-   * Effectively a shorthand for:
-   *
-   *     new HashSet(equals: identical, hashCode: identityHashCodeOf)
-   */
-  factory HashSet.identity() = _IdentityHashSet<E>;
-
-  /**
-   * Create a hash set containing all [elements].
-   *
-   * Creates a hash set as by `new HashSet<E>()` and adds each element of
-   * `elements` to this set in the order they are iterated.
-   *
-   * All the [elements] should be assignable to [E].
-   * The `elements` iterable itself may have any element type, so this
-   * constructor can be used to down-cast a `Set`, for example as:
-   *
-   *     Set<SuperType> superSet = ...;
-   *     Set<SubType> subSet =
-   *         new HashSet<SubType>.from(superSet.where((e) => e is SubType));
-   */
-  factory HashSet.from(Iterable elements) {
-    HashSet<E> result = new HashSet<E>();
-    for (E e in elements) result.add(e);
-    return result;
-  }
-
-  /**
-   * Provides an iterator that iterates over the elements of this set.
-   *
-   * The order of iteration is unspecified,
-   * but consistent between changes to the set.
-   */
-  Iterator<E> get iterator;
-}