Added nextIntRange to dartvm and dart2js.

tests/compiler/dart2js_extra/math_lib_prefix_test.dart

 // Copyright (c) 2011, 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.
 
 #library("math_lib_prefix_test");
 #import("dart:math", prefix: "foo");
 
 main() {
   Expect.equals(2.0, foo.sqrt(4));
   Expect.equals(2.25, foo.pow(1.5, 2.0));
 
   int i = new foo.Random().nextInt(256);
+  int r = new foo.Random().nextIntRange(1, 256);
   double d = new foo.Random().nextDouble();
   bool b = new foo.Random().nextBool();
 }