Clean up duplicate tests in web-animations-api

third_party/WebKit/LayoutTests/web-animations-api/w3c/resources/keyframes-test.js

-(function(){
-'use strict'
-
-function createElement() {
-  var element = document.createElement('div');
-  document.documentElement.appendChild(element);
-  return element;
-}
-
-function heldTiming(progress) {
-  return {
-    duration: 1000,
-    fill: 'forwards',
-    delay: -progress * 1000,
-  };
-}
-
-function assertAnimationStyles(keyframes, expectations, description) {
-  for (var progress in expectations) {
-    var element = createElement();
-    element.animate(keyframes, heldTiming(progress));
-    var computedStyle = getComputedStyle(element);
-    for (var property in expectations[progress]) {
-      assert_equals(computedStyle[property], expectations[progress][property],
-          property + ' at ' + (progress * 100) + '%' + (description ? ' ' + description : ''));
-    }
-  }
-}
-
-window.assertAnimationStyles = assertAnimationStyles;
-})();