Big merge from experimental to bleeding edge.

sdk/lib/_internal/compiler/implementation/util/link_implementation.dart

Index: sdk/lib/_internal/compiler/implementation/util/link_implementation.dart
diff --git a/sdk/lib/_internal/compiler/implementation/util/link_implementation.dart b/sdk/lib/_internal/compiler/implementation/util/link_implementation.dart
index 1a066b0b3c4bbfa3e7e7995db431b1a59a2102c0..491bd4438b81b8f91d52e302cd7deabe038baf1f 100644
--- a/sdk/lib/_internal/compiler/implementation/util/link_implementation.dart
+++ b/sdk/lib/_internal/compiler/implementation/util/link_implementation.dart
@@ -5,13 +5,21 @@
 part of util_implementation;
 
 class LinkIterator<T> implements Iterator<T> {
-  Link<T> current;
-  LinkIterator(Link<T> this.current);
-  bool get hasNext => !current.isEmpty;
-  T next() {
-    T result = current.head;
-    current = current.tail;
-    return result;
+  T _current;
+  Link<T> _link;
+
+  LinkIterator(Link<T> this._link);
+
+  T get current => _current;
+
+  bool moveNext() {
+    if (_link.isEmpty) {
+      _current = null;
+      return false;
+    }
+    _current = _link.head;
+    _link = _link.tail;
+    return true;
   }
 }