Changing return value of request animation frame.

lib/html/dart2js/html_dart2js.dart

Index: lib/html/dart2js/html_dart2js.dart
diff --git a/lib/html/dart2js/html_dart2js.dart b/lib/html/dart2js/html_dart2js.dart
index f470f2d78d2fae2350579d1fb027bc3ec56e26ce..05c9b92d53763afb653361828701fe800c69beef 100644
--- a/lib/html/dart2js/html_dart2js.dart
+++ b/lib/html/dart2js/html_dart2js.dart
@@ -17529,7 +17529,9 @@ class _WindowImpl extends _EventTargetImpl implements Window native "@*DOMWindow
    }
    if (this.requestAnimationFrame && this.cancelAnimationFrame) return;
    this.requestAnimationFrame = function(callback) {
-       return window.setTimeout(callback, 16 /* 16ms ~= 60fps */);
+      return window.setTimeout(function() {
+        callback(Date.now());
+      }, 16 /* 16ms ~= 60fps */);
    };
    this.cancelAnimationFrame = function(id) { clearTimeout(id); }
 ''';
@@ -29854,7 +29856,7 @@ interface Rect {
 
 // WARNING: Do not edit - generated code.
 
-typedef bool RequestAnimationFrameCallback(int time);
+typedef void RequestAnimationFrameCallback(int time);
 // 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.