events: fix bug listenerCount don't compare wrapped listener

When add listener by once, it will be wrapped into another function.
And when pass listener and there is just one event listener added by
once, it will return 0 even if passed listener equal wrapped event
listener.

Refs: nodejs#46523
PR-URL: nodejs#48592
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Minwoo Jung <nodecorelab@gmail.com>

lib/events.js

@@ -847,7 +847,7 @@ function listenerCount(type, listener) {
 
     if (typeof evlistener === 'function') {
       if (listener != null) {
-        return listener === evlistener ? 1 : 0;
+        return listener === evlistener || listener === evlistener.listener ? 1 : 0;
       }
 
       return 1;

test/parallel/test-events-listener-count-with-listener.js

@@ -12,6 +12,18 @@ assert.strictEqual(EE.listenerCount('event'), 0);
 assert.strictEqual(EE.listenerCount('event', handler), 0);
 assert.strictEqual(EE.listenerCount('event', anotherHandler), 0);
 
+EE.once('event', handler);
+
+assert.strictEqual(EE.listenerCount('event'), 1);
+assert.strictEqual(EE.listenerCount('event', handler), 1);
+assert.strictEqual(EE.listenerCount('event', anotherHandler), 0);
+
+EE.removeAllListeners('event');
+
+assert.strictEqual(EE.listenerCount('event'), 0);
+assert.strictEqual(EE.listenerCount('event', handler), 0);
+assert.strictEqual(EE.listenerCount('event', anotherHandler), 0);
+
 EE.on('event', handler);
 
 assert.strictEqual(EE.listenerCount('event'), 1);