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

sdk/lib/_internal/lib/js_array.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 _interceptors;
 
 /**
  * The interceptor class for [List]. The compiler recognizes this
  * class as an interceptor, and changes references to [:this:] to
  * actually use the receiver of the method, which is generated as an extra
@@ skipping 225 matching lines @@
 
   bool every(bool f(E element)) => IterableMixinWorkaround.every(this, f);
 
   Iterable<E> get reversed => IterableMixinWorkaround.reversedList(this);
 
   void sort([int compare(E a, E b)]) {
     checkMutable('sort');
     IterableMixinWorkaround.sortList(this, compare);
   }
 
-  void shuffle() {
-    IterableMixinWorkaround.shuffleList(this);
+  void shuffle([Random random]) {
+    IterableMixinWorkaround.shuffleList(this, random);
   }
 
   int indexOf(Object element, [int start = 0]) {
     return IterableMixinWorkaround.indexOfList(this, element, start);
   }
 
   int lastIndexOf(Object element, [int start]) {
     return IterableMixinWorkaround.lastIndexOfList(this, element, start);
   }
 
@@ skipping 47 matching lines @@
 }
 
 /**
  * Dummy subclasses that allow the backend to track more precise
  * information about arrays through their type. The CPA type inference
  * relies on the fact that these classes do not override [] nor []=.
  */
 class JSMutableArray extends JSArray implements JSMutableIndexable {}
 class JSFixedArray extends JSMutableArray {}
 class JSExtendableArray extends JSMutableArray {}