url: fix inconsistent port in url.resolveObject

This commit fixes bug where url.resolveObject returns conflicting
host and port values.

Fixes: #8213
Ref: #8872
PR-URL: #8214
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/url.js

@@ -564,8 +564,10 @@ Url.prototype.resolveObject = function(relative) {
 
   if (isRelAbs) {
     // it's absolute.
-    result.host = (relative.host || relative.host === '') ?
-                  relative.host : result.host;
+    if (relative.host || relative.host === '') {
+      result.host = relative.host;
+      result.port = relative.port;
+    }
     result.hostname = (relative.hostname || relative.hostname === '') ?
                       relative.hostname : result.hostname;
     result.search = relative.search;

test/parallel/test-url.js

@@ -1513,7 +1513,13 @@ var relativeTests2 = [
   //changeing auth
   ['http://diff:auth@www.example.com',
    'http://asdf:qwer@www.example.com',
-   'http://diff:auth@www.example.com/']
+   'http://diff:auth@www.example.com/'],
+
+  // changing port
+  ['https://example.com:81/',
+   'https://example.com:82/',
+   'https://example.com:81/']
+
 ];
 relativeTests2.forEach(function(relativeTest) {
   const a = url.resolve(relativeTest[1], relativeTest[0]);