Revert "Move toString() to collection classes."

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].
  *
  * The list elements must extend [LinkedListEntry].
  */
 class LinkedList<E extends LinkedListEntry<E>>
     extends IterableBase<E>
     implements _LinkedListLink {
-
   int _modificationCount = 0;
   int _length = 0;
   _LinkedListLink _next;
   _LinkedListLink _previous;
 
   /**
    * Construct a new empty linked list.
    */
   LinkedList() {
     _next = _previous = this;
@@ skipping 26 matching lines @@
    * If [entry] is not in the list, `false` is returned.
    */
   bool remove(E entry) {
     if (entry._list != this) return false;
     _unlink(entry);  // Unlink will decrement length.
     return true;
   }
 
   Iterator<E> get iterator => new _LinkedListIterator<E>(this);
 
-  // TODO(zarah) Remove this, and let it be inherited by IterableMixin
-  String toString() => IterableMixinWorkaround.toStringIterable(this, '{', '}');
+  String toString() => ToString.iterableToString(this);
 
   int get length => _length;
 
   void clear() {
     _modificationCount++;
     _LinkedListLink next = _next;
     while (!identical(next, this)) {
       E entry = next;
       next = entry._next;
       entry._next = entry._previous = entry._list = null;
@@ skipping 149 matching lines @@
     _list._insertAfter(this, entry);
   }
 
   /**
    * Insert an element before this.
    */
   void insertBefore(E entry) {
     _list._insertAfter(_previous, entry);
   }
 }