Updated mediawiki/extensions
Project: mediawiki/extensions/ContentTranslation  519ce486c31240493841508d7723dd2b87bce5a3

Fixed "can't modify frozen String (RuntimeError)" error

See
https://integration.wikimedia.org/ci/view/BrowserTests/job/browsertests-ContentTranslation-language-stage.wmflabs.org-linux-firefox/18/consoleFull

Change-Id: I079be2ca4a53d0e86fe6158875dbec407eb11fdc