src/third_party/mozjs-45/js/src/tests/ecma_6/extensions/shell.js

// NOTE: This only turns on 1.8.5 in shell builds.  The browser requires the
//       futzing in js/src/tests/browser.js (which only turns on 1.8, the most
//       the browser supports).
if (typeof version != 'undefined')
  version(185);