Small changes to make analyzer happy.

sdk/lib/collection/linked_list.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;
 
 
 /**
  * A linked list implementation, providing O(1) removal(unlink) of elements and
  * manual traversal through [next] and [previous].
@@ skipping 167 matching lines @@
 
 class _LinkedListLink {
   _LinkedListLink _next;
   _LinkedListLink _previous;
 }
 
 
 /**
  * Entry element for a [LinkedList]. Any entry must extend this class.
  */
-abstract class LinkedListEntry<E> implements _LinkedListLink {
+abstract class LinkedListEntry<E extends LinkedListEntry>
+    implements _LinkedListLink {
   LinkedList<E> _list;
   _LinkedListLink _next;
   _LinkedListLink _previous;
 
   /**
    * Get the list containing this element.
    */
   LinkedList<E> get list => _list;
 
   /**
@@ skipping 26 matching lines @@
     _list._insertAfter(this, entry);
   }
 
   /**
    * Insert an element before this.
    */
   void insertBefore(E entry) {
     _list._insertAfter(_previous, entry);
   }
 }