Function getOs

test/common/wpt.js:31–42

* Return one of three expected values * https://github.com/web-platform-tests/wpt/blob/1c6ff12/tools/wptrunner/wptrunner/tests/test_update.py#L953-L958 * @returns {'linux'|'mac'|'win'}

()

 * @returns {'linux'|'mac'|'win'}
 */
function getOs() {
  switch (os.type()) {
    case 'Linux':
      return 'linux';
    case 'Darwin':
      return 'mac';
    case 'Windows_NT':
      return 'win';
    default:
      throw new Error('Unsupported os.type()');
  }
}

// https://github.com/web-platform-tests/wpt/blob/b24eedd/resources/testharness.js#L3705
function sanitizeUnpairedSurrogates(str) {