code: function _setCurrentLanguage(newLanguageId) {
          var oldLanguageId = currentLanguageId;
          if (oldLanguageId === newLanguageId) {
              return;
          }
          currentLanguageId = newLanguageId;
          PreferencesImpl.manager.signalContextChanged(_buildContext(currentFilename, oldLanguageId),
                                                       _buildContext(currentFilename, newLanguageId));
      }
docs: @private
  This function is used internally to set the current language of the document.
  Both at the moment of opening the file and when the language is manually
  overriden.
  
  @param {string} newLanguageId The id of the language of the current editor.