Issue #1797360 by xjm: Remove t() from test assertions in language module

...rupal/language/Tests/LanguageBrowserDetectionUnitTest.php

...Drupal/language/Tests/LanguageDependencyInjectionTest.php

...s/language/lib/Drupal/language/Tests/LanguageListTest.php

...lib/Drupal/language/Tests/LanguageNegotiationInfoTest.php

...lib/Drupal/language/Tests/LanguagePathMonolingualTest.php

...guage/lib/Drupal/language/Tests/LanguageSwitchingTest.php

...upal/language/Tests/LanguageUILanguageNegotiationTest.php

...ge/lib/Drupal/language/Tests/LanguageUrlRewritingTest.php