[enzyme-adapter-utils] [New] Add event name mapping for transitionend

Fixes #1258.

Author: John Krueger

packages/enzyme-adapter-utils/src/Utils.js

@@ -41,6 +41,7 @@ export function mapNativeEventNames(event) {
     beforeinput: 'beforeInput',
     mouseenter: 'mouseEnter',
     mouseleave: 'mouseLeave',
+    transitionend: 'transitionEnd',
   };
 
   return nativeToReactEventMap[event] || event;