| <!DOCTYPE html> | 
 | <script src="../resources/testharness.js"></script> | 
 | <script src="../resources/testharnessreport.js"></script> | 
 |  | 
 | <script> | 
 | test(function() { | 
 |   document.timeline.playbackRate = 0; | 
 |   document.timeline.currentTime = 0; | 
 |   var player = document.documentElement.animate([], 1000); | 
 |   player.startTime = -1000; | 
 |  | 
 |   assert_equals(player.currentTime, 1000); | 
 |  | 
 |   player.effect.timing.duration = 1500; | 
 |   document.timeline.currentTime = 2000; | 
 |  | 
 |   assert_equals(player.startTime, -1000); | 
 |   assert_equals(player.currentTime, 1500); | 
 | }, 'Extending effect should not cause a change in start time.'); | 
 | </script> |