Move toString() to collection classes.

sdk/lib/collection/queue.dart

 // Copyright (c) 2011, 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 [Queue] is a collection that can be manipulated at both ends. One
  * can iterate over the elements of a queue through [forEach] or with
  * an [Iterator].
@@ skipping 282 matching lines @@
     while (!identical(entry, _sentinel)) {
       DoubleLinkedQueueEntry<E> nextEntry = entry._next;
       f(entry);
       entry = nextEntry;
     }
   }
 
   _DoubleLinkedQueueIterator<E> get iterator {
     return new _DoubleLinkedQueueIterator<E>(_sentinel);
   }
-
-  String toString() {
-    return ToString.iterableToString(this);
-  }
+  
+  // TODO(zarah)  Remove this, and let it be inherited by IterableBase
+  String toString() => IterableMixinWorkaround.toStringIterable(this);
 }
 
 class _DoubleLinkedQueueIterator<E> implements Iterator<E> {
   _DoubleLinkedQueueEntrySentinel<E> _sentinel;
   DoubleLinkedQueueEntry<E> _currentEntry = null;
   E _current;
 
   _DoubleLinkedQueueIterator(_DoubleLinkedQueueEntrySentinel<E> sentinel)
       : _sentinel = sentinel, _currentEntry = sentinel;
 
@@ skipping 205 matching lines @@
 
   void clear() {
     if (_head != _tail) {
       for (int i = _head; i != _tail; i = (i + 1) & (_table.length - 1)) {
         _table[i] = null;
       }
       _head = _tail = 0;
       _modificationCount++;
     }
   }
-
-  String toString() {
-    return ToString.iterableToString(this);
-  }
+  
+  // TODO(zarah)  Remove this, and let it be inherited by IterableBase
+  String toString() => IterableMixinWorkaround.toStringIterable(this);
 
   // Queue interface.
 
   void addLast(E element) { _add(element); }
 
   void addFirst(E element) {
     _head = (_head - 1) & (_table.length - 1);
     _table[_head] = element;
     if (_head == _tail) _grow();
     _modificationCount++;
@@ skipping 155 matching lines @@
     _queue._checkModification(_modificationCount);
     if (_position == _end) {
       _current = null;
       return false;
     }
     _current = _queue._table[_position];
     _position = (_position + 1) & (_queue._table.length - 1);
     return true;
   }
 }