URL: default port set to null after scheme update (#6346)

For whatwg/url#328.

Author: TimothyGu

url/setters_tests.json

@@ -259,6 +259,16 @@
                 "href": "view-source+data:text/html,<p>Test",
                 "protocol": "view-source+data:"
             }
+        },
+        {
+            "comment": "Port is set to null if it is the default for new scheme.",
+            "href": "http://foo.com:443/",
+            "new_value": "https",
+            "expected": {
+                "href": "https://foo.com/",
+                "protocol": "https:",
+                "port": ""
+            }
         }
     ],
     "username": [