http: do not loop over prototype in Agent

Fixes: #36364

PR-URL: #36410
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Ricky Zhou <0x19951125@gmail.com>

lib/_http_agent.js

@@ -428,7 +428,7 @@ Agent.prototype.removeSocket = function removeSocket(s, options) {
     // There might be older requests in a different origin, but
     // if the origin which releases the socket has pending requests
     // that will be prioritized.
-    for (const prop in this.requests) {
+    for (const prop of ObjectKeys(this.requests)) {
       // Check whether this specific origin is already at maxSockets
       if (this.sockets[prop] && this.sockets[prop].length) break;
       debug('removeSocket, have a request with different origin,' +