Allow EventTarget to use a different default target

src/ol/MapBrowserEventHandler.js

@@ -18,7 +18,7 @@ class MapBrowserEventHandler extends EventTarget {
    */
   constructor(map, moveTolerance) {
 
-    super();
+    super(map);
 
     /**
      * This is the element that we will listen to the real events on.

src/ol/events/Target.js

@@ -28,10 +28,20 @@ import {clear} from '../obj.js';
  *    returns false.
  */
 class Target extends Disposable {
-  constructor() {
+
+  /**
+   * @param {*=} opt_target Default event target for dispatched events.
+   */
+  constructor(opt_target) {
 
     super();
 
+    /**
+     * @private
+     * @type {*}
+     */
+    this.target_ = opt_target;
+
     /**
      * @private
      * @type {!Object<string, number>}
@@ -86,7 +96,7 @@ class Target extends Disposable {
     const evt = typeof event === 'string' ? new Event(event) : event;
     const type = evt.type;
     if (!evt.target) {
-      evt.target = this;
+      evt.target = this.target_ || this;
     }
     const listeners = this.listeners_[type];
     let propagate;

test/spec/ol/events/eventtarget.test.js

@@ -28,6 +28,15 @@ describe('ol.events.EventTarget', function() {
     it('creates an empty listeners_ object', function() {
       expect(Object.keys(eventTarget.listeners_)).to.have.length(0);
     });
+    it('accepts a default target', function(done) {
+      const defaultTarget = {};
+      const target = new EventTarget(defaultTarget);
+      target.addEventListener('my-event', function(event) {
+        expect(event.target).to.eql(defaultTarget);
+        done();
+      });
+      target.dispatchEvent('my-event');
+    });
   });
 
   describe('#hasListener', function() {