lib: make lowerProto scope more clear

PR-URL: #26562
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>

Author: gengjiawen

lib/url.js

@@ -249,10 +249,11 @@ Url.prototype.parse = function parse(url, parseQueryString, slashesDenoteHost) {
     }
   }
 
-  var proto = protocolPattern.exec(rest);
+  let proto = protocolPattern.exec(rest);
+  let lowerProto;
   if (proto) {
     proto = proto[0];
-    var lowerProto = proto.toLowerCase();
+    lowerProto = proto.toLowerCase();
     this.protocol = lowerProto;
     rest = rest.slice(proto.length);
   }