Web Animations: Fix error in clock update logic and re-enable timeline-time test

LayoutTests/web-animations-api/timeline-time.html

Index: LayoutTests/web-animations-api/timeline-time.html
diff --git a/LayoutTests/web-animations-api/timeline-time.html b/LayoutTests/web-animations-api/timeline-time.html
index abe1a6b562e27a6189f6c760310d45b55a2e6d1d..9c86843c31507f4ee5d51e3dd25c028f6b9d0fef 100644
--- a/LayoutTests/web-animations-api/timeline-time.html
+++ b/LayoutTests/web-animations-api/timeline-time.html
@@ -31,7 +31,7 @@ test(function() {
 
   requestAnimationFrame(function() {
     rafTest.step(function() {
-      assert_greater_than(document.timeline.currentTime, startTime);
+      assert_greater_than_equal(document.timeline.currentTime, startTime);
       firstRafTime = document.timeline.currentTime;
     });
   });
@@ -43,25 +43,4 @@ test(function() {
     rafTest.done();
   });
 })();
-
-(function() {
-  var rafTest = async_test('document.timeline.currentTime time should be consistent with the time value passed to RAF callbacks');
-  var firstRafTime;
-  var firstRafDelta;
-
-  requestAnimationFrame(function(t) {
-    rafTest.step(function() {
-      firstRafTime = document.timeline.currentTime;
-      firstRafDelta = document.timeline.currentTime - t;
-    });
-
-    requestAnimationFrame(function(t) {
-      rafTest.step(function() {
-        assert_greater_than(document.timeline.currentTime, firstRafTime);
-        assert_equals(document.timeline.currentTime - t, firstRafDelta);
-      });
-      rafTest.done();
-    });
-  });
-})();
 </script>