Un-skip MobileContextTest::testUpdateDesktopUrlHost

Hashar made this test skip a long time ago because I was running a URL
containing utf-8 characters through wfParseUrl() and there are known
issues with parse_url() and utf-8 stirngs
(https://bugs.php.net/bug.php?id=52923). I've been ignoring the skipped
tests for a long time, but I finally couldn't stand it anymore. I've
urlencdoed the utf-8 bits from the test URLs, which emulates what
happens in the actual code that uses these functions.

Change-Id: Iad39fac153d9f185e1112212742d75d97f4f4718
Merge "Un-skip MobileContextTest::testUpdateDesktopUrlHost"