Make List.shuffle take an optional Random object to use.

sdk/lib/_collection_dev/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.dev;
 
 /**
  * Mixin that throws on the length changing operations of [List].
  *
  * Intended to mix-in on top of [ListMixin] for fixed-length lists.
@@ skipping 122 matching lines @@
   void retainWhere(bool test(E element)) {
     throw new UnsupportedError(
         "Cannot remove from an unmodifiable list");
   }
 
   void sort([Comparator<E> compare]) {
     throw new UnsupportedError(
         "Cannot modify an unmodifiable list");
   }
 
-  void shuffle() {
+  void shuffle([Random random]) {
     throw new UnsupportedError(
         "Cannot modify an unmodifiable list");
   }
 
   void clear() {
     throw new UnsupportedError(
         "Cannot clear an unmodifiable list");
   }
 
   E removeAt(int index) {
@@ skipping 105 matching lines @@
 }
 
 class ReversedListIterable<E> extends ListIterable<E> {
   Iterable<E> _source;
   ReversedListIterable(this._source);
 
   int get length => _source.length;
 
   E elementAt(int index) => _source.elementAt(_source.length - 1 - index);
 }