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

pkg/third_party/html5lib/lib/src/list_proxy.dart

 // TODO(jmesserly): remove this once we have a subclassable growable list
 // in our libraries.
 
 /** A [List] proxy that you can subclass. */
 library list_proxy;
 
 import 'dart:collection';
+import 'dart:math' show Random;
 
 // TOOD(jmesserly): this needs to be removed, but fixing NodeList is tricky.
 class ListProxy<E> extends IterableBase<E> implements List<E> {
 
   /** The inner [List<T>] with the actual storage. */
   final List<E> _list;
 
   /**
    * Creates a list proxy.
    * You can optionally specify the list to use for [storage] of the items,
@@ skipping 26 matching lines @@
 
   // From List
   E operator [](int index) => _list[index];
   operator []=(int index, E value) { _list[index] = value; }
   set length(int value) { _list.length = value; }
   void add(E value) { _list.add(value); }
 
   void addLast(E value) { add(value); }
   void addAll(Iterable<E> collection) { _list.addAll(collection); }
   void sort([int compare(E a, E b)]) { _list.sort(compare); }
-  void shuffle() { _list.shuffle(); }
+  void shuffle([Random random]) { _list.shuffle(random); }
 
   int indexOf(E element, [int start = 0]) => _list.indexOf(element, start);
   int lastIndexOf(E element, [int start]) => _list.lastIndexOf(element, start);
   void clear() { _list.clear(); }
 
   E removeAt(int index) => _list.removeAt(index);
   E removeLast() => _list.removeLast();
 
   void removeWhere(bool test(E element)) => _list.removeWhere(test);
   void retainWhere(bool test(E element)) => _list.retainWhere(test);
@@ skipping 15 matching lines @@
   Map<int, E> asMap() => _list.asMap();
 
   void replaceRange(int start, int end, Iterable<E> newContents) =>
       _list.replaceRange(start, end, newContents);
 
   void setAll(int index, Iterable<E> iterable) => _list.setAll(index, iterable);
 
   void fillRange(int start, int end, [E fillValue])
       => _list.fillRange(start, end, fillValue);
 }