Make Iterable.toList more efficient if the length is known.

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 426 matching lines @@
 
 /**
  * List based [Queue].
  *
  * Keeps a cyclic buffer of elements, and grows to a larger buffer when
  * it fills up. This guarantees constant time peek and remove operations, and
  * amortized constant time add operations.
  *
  * The structure is efficient for any queue or stack usage.
  */
-class ListQueue<E> extends Iterable<E> implements Queue<E> {
+class ListQueue<E> extends ListIterable<E> implements Queue<E> {
   static const int _INITIAL_CAPACITY = 8;
   List<E> _table;
   int _head;
   int _tail;
   int _modificationCount = 0;
 
   /**
    * Create an empty queue.
    *
    * If [initialCapacity] is given, prepare the queue for at least that many
@@ skipping 13 matching lines @@
    * Create a `ListQueue` containing all [elements].
    *
    * The elements are added to the queue, as by [addLast], in the order given by
    * `elements.iterator`.
    *
    * All `elements` should be assignable to [E].
    */
   factory ListQueue.from(Iterable elements) {
     if (elements is List) {
       int length = elements.length;
-      ListQueue<E> queue = new ListQueue(length + 1);
+      ListQueue<E> queue = new ListQueue<E>(length + 1);
       assert(queue._table.length > length);
       for (int i = 0; i < length; i++) {
         queue._table[i] = elements[i] as Object/*=E*/;
       }
       queue._tail = length;
       return queue;
     } else {
       int capacity = _INITIAL_CAPACITY;
       if (elements is EfficientLength) {
         capacity = elements.length;
@@ skipping 323 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;
   }
 }