chore: simplify variable (#1332)

Author: godky

lib/request.js

@@ -287,11 +287,9 @@ module.exports = {
   get URL() {
     /* istanbul ignore else */
     if (!this.memoizedURL) {
-      const protocol = this.protocol;
-      const host = this.host;
       const originalUrl = this.originalUrl || ''; // avoid undefined in template string
       try {
-        this.memoizedURL = new URL(`${protocol}://${host}${originalUrl}`);
+        this.memoizedURL = new URL(`${this.origin}${originalUrl}`);
       } catch (err) {
         this.memoizedURL = Object.create(null);
       }