Revert "Move toString() to collection classes."

sdk/lib/collection/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;
 
 /**
  * Abstract implementation of a list.
  *
  * All operations are defined in terms of `length`, `operator[]`,
@@ skipping 10 matching lines @@
  * `operator[]` members. It implements write operations using those and
  * `length=` and `operator[]=`
  *
  * A fixed-length list should mix this class in, and the [FixedLengthListMixin]
  * as well, in that order, to overwrite the methods that modify the length.
  *
  * An unmodifiable list should mix [UnmodifiableListMixin] on top of this
  * mixin to prevent all modifications.
  */
 abstract class ListMixin<E> implements List<E> {
-  // A list to identify cyclic lists during toString() calls. 
-  static List _toStringList = new List();
-  
   // Iterable interface.
   Iterator<E> get iterator => new ListIterator<E>(this);
 
   E elementAt(int index) => this[index];
 
   void forEach(void action(E element)) {
     int length = this.length;
     for (int i = 0; i < length; i++) {
       action(this[i]);
       if (length != this.length) {
@@ skipping 429 matching lines @@
       setRange(index, index + iterable.length, iterable);
     } else {
       for (E element in iterable) {
         this[index++] = element;
       }
     }
   }
 
   Iterable<E> get reversed => new ReversedListIterable(this);
 
-  String toString() {
-    for (int i = 0; i < _toStringList.length; i++) {
-      if (identical(_toStringList[i], this)) { return '[...]'; }
-    }
-
-    var result = new StringBuffer();
-    try {
-      _toStringList.add(this);
-      result.write('[');
-      result.writeAll(this, ', ');
-      result.write(']');
-     } finally {
-       assert(identical(_toStringList.last, this));
-       _toStringList.removeLast();  
-     }
-     
-    return result.toString();
-  }
+  String toString() => ToString.iterableToString(this);
 }