static get meta() {
    return {
      id: 'preload-as',
      title: 'Preloaded requests have proper `as` attributes',
      failureTitle: 'Some preloaded requests do not have proper `as` attributes',
      description: '`<link rel=preload>` tags need an `as` attribute to specify the type of ' +
          'content being loaded.',

      // The name of the artifact provides input to this audit.
      requiredArtifacts: ['LinkElements'],
    };
  }
@fileoverview A fake additional check of the robots.txt file.