dgram: skip dns lookup for IPs

Previously, we would call dns.lookup even for IP addresses
in Socket#connect. This now skips that to improve performance.

Fixes: nodejs#39468

lib/dgram.js

@@ -39,6 +39,7 @@ const {
   newHandle,
 } = require('internal/dgram');
 const { guessHandleType } = internalBinding('util');
+const { isIP } = require('internal/net');
 const {
   ERR_INVALID_ARG_TYPE,
   ERR_MISSING_ARGS,
@@ -403,6 +404,19 @@ function _connect(port, address, callback) {
   if (callback)
     this.once('connect', callback);
 
+  // If host is an IP, skip performing a lookup.
+  const addressType = isIP(address);
+  if (addressType) {
+    defaultTriggerAsyncIdScope(this[async_id_symbol], process.nextTick, () => {
+      defaultTriggerAsyncIdScope(
+        this[async_id_symbol],
+        doConnect,
+        null, this, address, address, port, callback
+      );
+    });
+    return;
+  }
+
   const afterDns = (ex, ip) => {
     defaultTriggerAsyncIdScope(
       this[async_id_symbol],