Use iterator, moveNext(), current.

sdk/lib/core/sequences.dart

Index: sdk/lib/core/sequences.dart
diff --git a/sdk/lib/core/sequences.dart b/sdk/lib/core/sequences.dart
index 32a3b4088ef23cea008323f4662884c5b151a635..5a0af69405def37a61b485747e3baf2f340cd0e1 100644
--- a/sdk/lib/core/sequences.dart
+++ b/sdk/lib/core/sequences.dart
@@ -33,7 +33,7 @@ abstract class Sequence<T> {
 abstract class SequenceCollection<E> implements Collection<E>, Sequence<E> {
   // The class is intended for use as a mixin as well.
 
-  Iterator<E> iterator() => new SequenceIterator(sequence);
+  Iterator<E> get iterator => new SequenceIterator(sequence);
 
   void forEach(f(E element)) {
     for (int i = 0; i < this.length; i++) f(this[i]);
@@ -194,10 +194,18 @@ class SequenceList<E> extends SequenceCollection<E> implements List<E> {
 class SequenceIterator<E> implements Iterator<E> {
   Sequence<E> _sequence;
   int _position;
-  SequenceIterator(this._sequence) : _position = 0;
-  bool get hasNext => _position < _sequence.length;
-  E next() {
-    if (hasNext) return _sequence[_position++];
+  SequenceIterator(this._sequence) : _position = -1;
+  bool moveNext() {
+    _position++;
+    if (_position < _sequence.length) return true;
+    _position = _sequence.length;
+    return false;
+  }
+  E get current {
+    if (0 <= _position && _position < _sequence.length) {
+      return _sequence[_position];
+    }
+    // TODO(floitsch): adapt error-message.
     throw new StateError("No more elements");
   }
 }