has-tostringtag 
Determine if the JS environment has Symbol.toStringTag support. Supports spec, or shams.
Example
var hasSymbolToStringTag = require('has-tostringtag');
hasSymbolToStringTag() === true; // if the environment has native Symbol.toStringTag support. Not polyfillable, not forgeable.
var hasSymbolToStringTagKinda = require('has-tostringtag/shams');
hasSymbolToStringTagKinda() === true; // if the environment has a Symbol.toStringTag sham that mostly follows the spec.Supported Symbol shams
Tests
Simply clone the repo, npm install, and run npm test