message: Polyfill Symbol.asyncIterator
diff: @@ -30,6 +30,11 @@ import {indent, prompt} from '../util';
  const logger = logging.getLogger('cli.lint');
  +if (Symbol.asyncIterator === undefined) {
  + // tslint:disable-next-line: no-any polyfilling.
  + (Symbol as any).asyncIterator = Symbol('asyncIterator');
  +}
  +
  export async function lint(options: Options, config: ProjectConfig) {
  const lintOptions: Partial<typeof config.lint> = (config.lint || {});
  