I guess the trailing dot at the selector of
.mwe-upwiz-details-filename. { overflow: hidden; width: 350px; }
in dir.combined[.min].css is an unwanted typo, not some dark browser-compatibility magic.
Good catch, fixed in r76697
$module['languageScripts'][$langCode] is added incorrectly at [1], it contains a filename (e.g. resources/languages/classes/LanguageCs.js), but is added verbatim to HTML output as an inline script. See the HTML code of [2].
$module['languageScripts'][$langCode]
resources/languages/classes/LanguageCs.js