Test is failing on IE11

Author: davidblurton

seamless-immutable.development.js

@@ -471,12 +471,13 @@
     return makeImmutable(obj, mutatingObjectMethods);
   }
 
-  var REACT_ELEMENT_TYPE = (typeof Symbol === 'function' && Symbol.for && Symbol.for('react.element')) || 0xeac7;
+  var REACT_ELEMENT_TYPE = typeof Symbol === 'function' && Symbol.for && Symbol.for('react.element')
+  var REACT_ELEMENT_TYPE_FALLBACK = 0xeac7;
 
   function isReactElement(obj) {
     return obj.hasOwnProperty &&
            obj.hasOwnProperty('$$typeof') &&
-           obj.$$typeof === REACT_ELEMENT_TYPE;
+           obj.$$typeof === REACT_ELEMENT_TYPE_FALLBACK || obj.$$typeof === REACT_ELEMENT_TYPE;
   }
 
   function Immutable(obj, options) {