Revert of All changes to ui/webui/ from bookmarks CL that block other CLs

ui/webui/resources/js/cr/event_target.js

Index: ui/webui/resources/js/cr/event_target.js
diff --git a/ui/webui/resources/js/cr/event_target.js b/ui/webui/resources/js/cr/event_target.js
index 6a73f1ff95a8b9d8a9adebfdadc797385b10763c..0d6fbd58adef11a886e548167ea7cd59456e0613 100644
--- a/ui/webui/resources/js/cr/event_target.js
+++ b/ui/webui/resources/js/cr/event_target.js
@@ -6,11 +6,6 @@
  * @fileoverview This contains an implementation of the EventTarget interface
  * as defined by DOM Level 2 Events.
  */
-
-/**
- * @typedef {EventListener|function(!Event):(boolean|undefined)}
- */
-var EventListenerType;
 
 cr.define('cr', function() {
 
@@ -28,8 +23,8 @@
     /**
      * Adds an event listener to the target.
      * @param {string} type The name of the event.
-     * @param {EventListenerType} handler The handler for the event. This is
-     *     called when the event is dispatched.
+     * @param {!Function|{handleEvent:Function}} handler The handler for the
+     *     event. This is called when the event is dispatched.
      */
     addEventListener: function(type, handler) {
       if (!this.listeners_)
@@ -46,7 +41,8 @@
     /**
      * Removes an event listener from the target.
      * @param {string} type The name of the event.
-     * @param {EventListenerType} handler The handler for the event.
+     * @param {!Function|{handleEvent:Function}} handler The handler for the
+     *     event.
      */
     removeEventListener: function(type, handler) {
       if (!this.listeners_)