Move some core classes to collection library.

sdk/lib/core/iterator.dart

Index: sdk/lib/core/iterator.dart
diff --git a/sdk/lib/core/iterator.dart b/sdk/lib/core/iterator.dart
index 12c4a72a97652d78177ab6c1b19b93d73ec2716f..e251df62fb35a052c90f29c69f314d99e64e2bcb 100644
--- a/sdk/lib/core/iterator.dart
+++ b/sdk/lib/core/iterator.dart
@@ -16,6 +16,13 @@ part of dart.core;
  * accessing the first element the iterator must thus be advanced ([moveNext])
  * to point to the first element. If there is no element left, then [moveNext]
  * returns false.
+ *
+ * A typical usage of an [Iterator] looks as follows:
+ *
+ *     var it = obj.iterator;
+ *     while (it.moveNext()) {
+ *       use(it.current);
+ *     }
  */
 abstract class Iterator<E> {
   /**
@@ -36,37 +43,3 @@ abstract class Iterator<E> {
    */
   E get current;
 }
-
-class HasNextIterator<E> {
-  static const int _HAS_NEXT_AND_NEXT_IN_CURRENT = 0;
-  static const int _NO_NEXT = 1;
-  static const int _NOT_MOVED_YET = 2;
-
-  Iterator _iterator;
-  int _state = _NOT_MOVED_YET;
-
-  HasNextIterator(this._iterator);
-
-  bool get hasNext {
-    if (_state == _NOT_MOVED_YET) _move();
-    return _state == _HAS_NEXT_AND_NEXT_IN_CURRENT;
-  }
-
-  E next() {
-    // Call to hasNext is necessary to make sure we are positioned at the first
-    // element when we start iterating.
-    if (!hasNext) throw new StateError("No more elements");
-    assert(_state == _HAS_NEXT_AND_NEXT_IN_CURRENT);
-    E result = _iterator.current;
-    _move();
-    return result;
-  }
-
-  void _move() {
-    if (_iterator.moveNext()) {
-      _state = _HAS_NEXT_AND_NEXT_IN_CURRENT;
-    } else {
-      _state = _NO_NEXT;
-    }
-  }
-}