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

pkg/unmodifiable_collection/lib/unmodifiable_collection.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.
 
 /**
  * Wrappers that prevent List, Set, or Map objects from being modified.
  *
  * The [Set] and [Map] wrappers allow reading from the wrapped collection,
  * but prohibit writing.
  *
  * The [List] wrapper prevents changes to the length of the wrapped list,
  * but allows changes to the contents.
  */
 library unmodifiable_collection;
 
+import "dart:math" show Random;
 export "dart:collection" show UnmodifiableListView;
 
 /**
  * A fixed-length list.
  *
  * A NonGrowableListView contains a [List] object and ensures that
  * its length does not change.
  * Methods that would change the length of the list,
  * such as [add] and [remove], throw an [UnsupportedError].
  *
@@ skipping 25 matching lines @@
   List<E> sublist(int start, [int end]) => _source.sublist(start, end);
 
   Iterable<E> get reversed => _source.reversed;
 
   Map<int, E> asMap() => _source.asMap();
 
   void operator []=(int index, E value) { _source[index] = value; }
 
   void sort([int compare(E a, E b)]) { _source.sort(compare); }
 
-  void shuffle() { _source.shuffle(); }
+  void shuffle([Random random]) { _source.shuffle(random); }
 
   void setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]) {
     _source.setRange(start, end, iterable, skipCount);
   }
 
   void fillRange(int start, int end, [E fillValue]) {
     _source.fillRange(start, end, fillValue);
   }
 
   void setAll(int index, Iterable<E> iterable) {
@@ skipping 277 matching lines @@
   Iterable<E> take(int n) => _source.take(n);
 
   Iterable<E> takeWhile(bool test(E value)) => _source.takeWhile(test);
 
   List<E> toList({ bool growable: true }) => _source.toList(growable: growable);
 
   Set<E> toSet() => _source.toSet();
 
   Iterable<E> where(bool test(E element)) => _source.where(test);
 }