code: function adjustOldProperty(config) {
      if (!config.input.cssSource && 'cssRoot' in config.input) {
          config.input.cssSource = config.input.cssRoot;
          delete config.input.cssRoot;
      }
      if (!config.output.cssDist && 'cssRoot' in config.output) {
          config.output.cssDist = config.output.cssRoot;
          delete config.output.cssRoot;
      }
      if (!config.output.imageDist && 'imageRoot' in config.output) {
          config.output.imageDist = config.output.imageRoot;
          delete config.output.imageRoot;
      }
      if (!config.output.maxSingleSize && 'maxSize' in config.output) {
          config.output.maxSingleSize = config.output.maxSize;
          delete config.output.maxSize;
      }
      return config;
  }
docs: 对旧的配置项做兼容
  @param  {Config} config
  @return {Config}