Add internal operation that converts a growable list to a fixed list.

sdk/lib/core/list.dart

 // Copyright (c) 2012, 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.core;
 
 /**
  * An indexable collection of objects with a length.
  *
  * Subclasses of this class implement different kinds of lists.
@@ skipping 78 matching lines @@
    *
    * This constructor returns a growable list if [growable] is true;
    * otherwise, it returns a fixed-length list.
    */
   factory List.from(Iterable other, { bool growable: true }) {
     List<E> list = new List<E>();
     for (E e in other) {
       list.add(e);
     }
     if (growable) return list;
-    int length = list.length;
-    List<E> fixedList = new List<E>(length);
-    for (int i = 0; i < length; i++) {
-      fixedList[i] = list[i];
-    }
-    return fixedList;
+    return makeListFixedLength(list);
   }
 
   /**
    * Generates a list of values.
    *
    * Creates a list with [length] positions and fills it with values created by
    * calling [generator] for each index in the range `0` .. `length - 1`
    * in increasing order.
    *
    *     new List<int>.generate(3, (int index) => index * index); // [0, 1, 4]
@@ skipping 344 matching lines @@
    * as values. The `Map.keys` [Iterable] iterates the indices of this list
    * in numerical order.
    *
    *     List<String> words = ['fee', 'fi', 'fo', 'fum'];
    *     Map<int, String> map = words.asMap();
    *     map[0] + map[1];   // 'feefi';
    *     map.keys.toList(); // [0, 1, 2, 3]
    */
   Map<int, E> asMap();
 }