Style cleanup in animation layout test.

third_party/WebKit/LayoutTests/web-animations-api/animation-cancel-ready-finished-ordering.html

Index: third_party/WebKit/LayoutTests/web-animations-api/animation-cancel-ready-finished-ordering.html
diff --git a/third_party/WebKit/LayoutTests/web-animations-api/animation-cancel-ready-finished-ordering.html b/third_party/WebKit/LayoutTests/web-animations-api/animation-cancel-ready-finished-ordering.html
index 38489f1601571ea738ca8e0c0a51e41b8fe966ad..db0be86a310ef30eecc560f52b7693d56a711065 100644
--- a/third_party/WebKit/LayoutTests/web-animations-api/animation-cancel-ready-finished-ordering.html
+++ b/third_party/WebKit/LayoutTests/web-animations-api/animation-cancel-ready-finished-ordering.html
@@ -8,12 +8,12 @@
 async_test(function(t) {
   var animation = document.documentElement.animate([], 100000);
   var ready = false;
-  animation.ready.then(null, function() {
+  animation.ready.catch(function() {
     t.step(function() {
       ready = true;
     });
   });
-  animation.finished.then(null, function() {
+  animation.finished.catch(function() {
     t.step(function() {
       assert_true(ready);
     });