events: check if _events is an own property

Without this check it is possible to have the _events object shared
amongst instances.

Fixes #7157

Signed-off-by: Trevor Norris <trev.norris@gmail.com>

lib/events.js

@@ -49,7 +49,10 @@ EventEmitter.init = function() {
       this.domain = domain.active;
     }
   }
-  this._events = this._events || {};
+
+  if (!this._events || this._events === Object.getPrototypeOf(this)._events)
+    this._events = {};
+
   this._maxListeners = this._maxListeners || undefined;
 };
 

test/simple/test-event-emitter-subclass.js

@@ -53,3 +53,17 @@ process.on('exit', function() {
   assert.deepEqual(myee._events, {});
   console.log('ok');
 });
+
+
+function MyEE2() {
+  EventEmitter.call(this);
+}
+
+MyEE2.prototype = new EventEmitter();
+
+var ee1 = new MyEE2();
+var ee2 = new MyEE2();
+
+ee1.on('x', function () {});
+
+assert.equal(EventEmitter.listenerCount(ee2, 'x'), 0);