Remove CSSKeyframesRule.insertRule()

LayoutTests/animations/change-keyframes.html

Index: LayoutTests/animations/change-keyframes.html
diff --git a/LayoutTests/animations/change-keyframes.html b/LayoutTests/animations/change-keyframes.html
index 0acbf6d2559bdc6fc191114f9dbc8a9e87c35f07..a7358b8f51d44b4f0a94b52e69a8fa45ee189eef 100644
--- a/LayoutTests/animations/change-keyframes.html
+++ b/LayoutTests/animations/change-keyframes.html
@@ -57,10 +57,10 @@
           keyframes.deleteRule("40%");
           keyframes.deleteRule("60%");
           keyframes.deleteRule("100%");
-          keyframes.insertRule("0% { top: 50px; }");
-          keyframes.insertRule("10% { top: 100px; }");
-          keyframes.insertRule("90% { top: 100px; }");
-          keyframes.insertRule("100% { top: 150px; }");
+          keyframes.appendRule("0% { top: 50px; }");
+          keyframes.appendRule("10% { top: 100px; }");
+          keyframes.appendRule("90% { top: 100px; }");
+          keyframes.appendRule("100% { top: 150px; }");
           document.getElementById('box').style.webkitAnimationName = "anim";
       }
     }