Domain prefix multilanguage alias bug

Repeatable: Always

Steps to repeat:
- Enable Domain Access and Domain Prefix
- Enable i18n
- Enable two or more languages (eg: en, it) and configure "Language negotiation" with option "Path prefix only"
- In Multilingual system set Content selection to "All content. No language conditions apply"
- Configure two or more domains (eg: http://example.com, http://sub.example.com)
- Prefixing {url_alias} table
- Create a page on the source domain with source language (eg: en), don't check "Send to all affiliates", publish to source domain (eg: http://example.com) and set an URL path (eg: test)
- Create a page on the other domain, don't check "Send to all affiliates", publish to this domain (eg: http://sub.example.com) and output a link via the l() function (eg: php print l('test', 'node/1');)
- Visit the page with secondary language (eg: it) and check the output URL

Expected Results:
The link is it/node/1

Actual Results:
The link is it/test, wich cause a Not Found error

The problem seems to be in the domain_prefix_domainpath() function [domain_prefix.path.inc], which doesn't control the alias language.
The attached patch fixes this problem (borrowed from drupal_lookup_path() [path.inc]).