Merge pull request #442 from hypothesis/add-symbol-polyfill

Add Symbol polyfill

src/shared/polyfills.js

@@ -3,6 +3,7 @@
 // ES2015 polyfills
 require('core-js/es6/promise');
 require('core-js/es6/set');
+require('core-js/es6/symbol');
 require('core-js/fn/array/find');
 require('core-js/fn/array/find-index');
 require('core-js/fn/array/from');