Remove unused code

components/util/index.jsx

@@ -1,41 +0,0 @@
-import { Dom } from 'rc-util';
-
-export let transitionEndEvent = whichTransitionEvent();
-export let animationEndEvent = whichAnimationEvent();
-
-function whichTransitionEvent() {
-  const transitions = {
-    'transition': 'transitionend',
-    'OTransition': 'oTransitionEnd',
-    'MozTransition': 'transitionend',
-    'WebkitTransition': 'webkitTransitionEnd'
-  };
-  for (let t in transitions) {
-    if (t in document.documentElement.style) {
-      return transitions[t];
-    }
-  }
-  return false;
-}
-
-function whichAnimationEvent() {
-  const animation = {
-    'animation': 'animationend',
-    'OAnimation': 'oAnimationEnd',
-    'MozAnimation': 'animationend',
-    'WebkitAnimation': 'webkitAnimationEnd'
-  };
-  for (let t in animation) {
-    if (t in document.documentElement.style) {
-      return animation[t];
-    }
-  }
-  return false;
-}
-
-export let addEventListenerOnce = function(element, type, handler) {
-  var eventListener = Dom.addEventListener(element, type, function(event) {
-    eventListener && eventListener.remove();
-    handler(event);
-  });
-};