message: Define getLanguageFromBrowser() for LanguageDropdown
  Without it we can't compile, so we should define it. It looks like it's never been defined, and LanguageDropdown seems to use it as a last resort - it should be safe to land.
diff: @@ -336,6 +336,10 @@ export function getLanguagesFromBrowser() {
  return [navigator.userLanguage || "en"];
  }
  +export function getLanguageFromBrowser() {
  + return getLanguagesFromBrowser()[0];
  +}
  +
  /**
  * Turns a language string, normalises it,
  * (see normalizeLanguageKey) into an array of language strings
  