Remove the not needed wfGetLangObj( $expected )->getCode().
This just converts the language code to a Language object and back to a
language code.
Remove the test case [ CONTENT_MODEL_JAVASCRIPT, 'javascript' ].
This test case was successful because CONTENT_MODEL_JAVASCRIPT gets
interpreted as title 'javascript' and 'javascript' gets interpreted as
an invalid language code which gets replaced by
wfGetLangObj( 'javascript' )->getCode() to $wgLanguageCode.
Remove the not needed is_string check. All titles are strings.
Change-Id: I77f6c061190f94e1d6d8b3a0662a497ed2e94795
da02313ae9