Add SplayTreeSet.

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 IterableBase<E> implements Set<E> {
 
   // Set.
   bool containsAll(Iterable<Object> other) {
     for (Object object in other) {
       if (!this.contains(object)) return false;
     }
     return true;
   }
 
   /** Create a new Set of the same type as this. */
   HashSet<E> _newSet();
 
   Set<E> intersection(Set<Object> other) {
     Set<E> result = _newSet();
-    if (other.length < this.length) {
-      for (var element in other) {
-        if (this.contains(element)) result.add(element);
-      }
-    } else {
-      for (E element in this) {
-        if (other.contains(element)) result.add(element);
-      }
+    for (var element in this) {
+      if (other.contains(element)) result.add(element);
     }
     return result;
   }
 
   Set<E> union(Set<E> other) {
     return _newSet()..addAll(this)..addAll(other);
   }
 
   Set<E> difference(Set<E> other) {
     HashSet<E> result = _newSet();
@@ skipping 81 matching lines @@
   /**
    * Create a hash set containing the elements of [iterable].
    *
    * Creates a hash set as by `new HashSet<E>()` and adds each element of
    * `iterable` to this set in the order they are iterated.
    */
   factory HashSet.from(Iterable<E> iterable) {
     return new HashSet<E>()..addAll(iterable);
   }
 }