url: restrict setting protocol to "file"

Since file URLs can not have `username/password/port`,
the specification was updated to restrict setting protocol to "file".

Refs: whatwg/url#269
Fixes: nodejs#11785
PR-URL: nodejs#11887
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

lib/internal/url.js

@@ -133,6 +133,13 @@ function onParseProtocolComplete(flags, protocol, username, password,
   if ((s && !newIsSpecial) || (!s && newIsSpecial)) {
     return;
   }
+  if (protocol === 'file:' &&
+    (ctx.username || ctx.password || ctx.port !== undefined)) {
+    return;
+  }
+  if (ctx.scheme === 'file:' && !ctx.host) {
+    return;
+  }
   if (newIsSpecial) {
     ctx.flags |= binding.URL_FLAGS_SPECIAL;
   } else {