code: function _buildPreferencesContext(fullPath) {
          return PreferencesManager._buildContext(fullPath,
              fullPath ? LanguageManager.getLanguageForPath(fullPath).getId() : undefined);
      }
docs: Helper function to build preferences context based on the full path of
  the file.
  
  @param {string} fullPath Full path of the file
  
  @return {*} A context for the specified file name