$ npm install intl-fallback-symbolECMA-402 Intl spec's internal FallbackSymbol.
This Symbol is well-known - shared across realms.
It is present in the following engines with the description "IntlLegacyConstructedSymbol" (spec):
It is present in the following engines with the description "IntlFallback": (The ES2017 Intl spec did not specify a description)
When it is present, the package will export it; when not, it will export undefined.
var IntlFallbackSymbol = require('intl-fallback-symbol');
var assert = require('assert');
assert(typeof IntlFallbackSymbol === 'symbol');
Simply clone the repo, npm install, and run npm test