just add this polyfill (taken from cdn.polyfill.io)
(function(undefined) { // Symbol // A modification of https://github.com/WebReflection/get-own-property-symbols // (C) Andrea Giammarchi - MIT Licensed (function(Object, GOPS, global) { var setDescriptor; var id = 0; var random = '' + Math.random(); var prefix = '__\x01symbol:'; var prefixLength = prefix.length; var internalSymbol = '__\ x01symbol@ @' + random; var DP = 'defineProperty'; var DPies = 'defineProperties'; var GOPN = 'getOwnPropertyNames'; var GOPD = 'getOwnPropertyDescriptor'; var PIE = 'propertyIsEnumerable'; var ObjectProto = Object.prototype; var hOP = ObjectProto.hasOwnProperty; var pIE = ObjectProto[PIE]; var toString = ObjectProto.toString; var concat = Array.prototype.concat; var cachedWindowNames = typeof window === 'object' ? Object.getOwnPropertyNames(window) : []; var nGOPN = Object[GOPN]; var gOPN = function getOwnPropertyNames(obj) { if (toString.call(obj) === '[object Window]') { try { return nGOPN(obj); } catch (e) { // IE bug where layout engine calls userland gOPN for cross-domain 'window' objects return concat.call([], cachedWindowNames); } } return nGOPN(obj); }; var gOPD = Object[GOPD]; var create = Object.create; var keys = Object.keys; var freeze = Object.freeze || Object; var defineProperty = Object[DP]; var $defineProperties = Object[DPies]; var descriptor = gOPD(Object, GOPN); var addInternalIfNeeded = function(o, uid, enumerable) { if (!hOP.call(o, internalSymbol)) { try { defineProperty(o, internalSymbol, { enumerable: false, configurable: false, writable: false, value: {} }); } catch (e) { o[internalSymbol] = {}; } } o[internalSymbol]['@@' + uid] = enumerable; }; var createWithSymbols = function(proto, descriptors) { var self = create(proto); gOPN(descriptors).forEach(function(key) { if (propertyIsEnumerable.call(descriptors, key)) { $defineProperty(self, key, descriptors[key]); } }); return self; }; var copyAsNonEnumerable = function(descriptor) { var newDescriptor = create(descriptor); newDescriptor.enumerable = false; return newDescriptor; }; var get = function get() {}; var onlyNonSymbols = function(name) { return name != internalSymbol && !hOP.call(source, name); }; var onlySymbols = function(name) { return name != internalSymbol && hOP.call(source, name); }; var propertyIsEnumerable = function propertyIsEnumerable(key) { var uid = '' + key; return onlySymbols(uid) ? ( hOP.call(this, uid) && this[internalSymbol]['@@' + uid] ) : pIE.call(this, key); }; var setAndGetSymbol = function(uid) { var descriptor = { enumerable: false, configurable: true, get: get, set: function(value) { setDescriptor(this, uid, { enumerable: false, configurable: true, writable: true, value: value }); addInternalIfNeeded(this, uid, true); } }; try { defineProperty(ObjectProto, uid, descriptor); } catch (e) { ObjectProto[uid] = descriptor.value; } return freeze(source[uid] = defineProperty( Object(uid), 'constructor', sourceConstructor )); }; var Symbol = function Symbol(description) { if (this instanceof Symbol) { throw new TypeError('Symbol is not a constructor'); } return setAndGetSymbol( prefix.concat(description || '', random, ++id) ); }; var source = create(null); var sourceConstructor = { value: Symbol }; var sourceMap = function(uid) { return source[uid]; }; var $defineProperty = function defineProp(o, key, descriptor) { var uid = '' + key; if (onlySymbols(uid)) { setDescriptor(o, uid, descriptor.enumerable ? copyAsNonEnumerable(descriptor) : descriptor); addInternalIfNeeded(o, uid, !!descriptor.enumerable); } else { defineProperty(o, key, descriptor); } return o; }; var onlyInternalSymbols = function(obj) { return function(name) { return hOP.call(obj, internalSymbol) && hOP.call(obj[internalSymbol], '@@' + name); }; }; var $getOwnPropertySymbols = function getOwnPropertySymbols(o) { return gOPN(o).filter(o === ObjectProto ? onlyInternalSymbols(o) : onlySymbols).map(sourceMap); }; descriptor.value = $defineProperty; defineProperty(Object, DP, descriptor); descriptor.value = $getOwnPropertySymbols; defineProperty(Object, GOPS, descriptor); descriptor.value = function getOwnPropertyNames(o) { return gOPN(o).filter(onlyNonSymbols); }; defineProperty(Object, GOPN, descriptor); descriptor.value = function defineProperties(o, descriptors) { var symbols = $getOwnPropertySymbols(descriptors); if (symbols.length) { keys(descriptors).concat(symbols).forEach(function(uid) { if (propertyIsEnumerable.call(descriptors, uid)) { $defineProperty(o, uid, descriptors[uid]); } }); } else { $defineProperties(o, descriptors); } return o; }; defineProperty(Object, DPies, descriptor); descriptor.value = propertyIsEnumerable; defineProperty(ObjectProto, PIE, descriptor); descriptor.value = Symbol; defineProperty(global, 'Symbol', descriptor); // defining 'Symbol.for(key)' descriptor.value = function(key) { var uid = prefix.concat(prefix, key, random); return uid in ObjectProto ? source[uid] : setAndGetSymbol(uid); }; defineProperty(Symbol, 'for', descriptor); // defining 'Symbol.keyFor(symbol)' descriptor.value = function(symbol) { if (onlyNonSymbols(symbol)) throw new TypeError(symbol + ' is not a symbol'); return hOP.call(source, symbol) ? symbol.slice(prefixLength * 2, -random.length) : void 0; }; defineProperty(Symbol, 'keyFor', descriptor); descriptor.value = function getOwnPropertyDescriptor(o, key) { var descriptor = gOPD(o, key); if (descriptor && onlySymbols(key)) { descriptor.enumerable = propertyIsEnumerable.call(o, key); } return descriptor; }; defineProperty(Object, GOPD, descriptor); descriptor.value = function(proto, descriptors) { return arguments.length === 1 || typeof descriptors === "undefined" ? create(proto) : createWithSymbols(proto, descriptors); }; defineProperty(Object, 'create', descriptor); descriptor.value = function() { var str = toString.call(this); return (str === '[object String]' && onlySymbols(this)) ? '[object Symbol]' : str; }; defineProperty(ObjectProto, 'toString', descriptor); setDescriptor = function(o, key, descriptor) { var protoDescriptor = gOPD(ObjectProto, key); delete ObjectProto[key]; defineProperty(o, key, descriptor); if (o !== ObjectProto) { defineProperty(ObjectProto, key, protoDescriptor); } }; }(Object, 'getOwnPropertySymbols', this));}).call('object' === typeof window && window || 'object' === typeof self && self || 'object' === typeof global && global || {});