Fix getWrappedInstance test

Single ref access cannot work anymore. Prefer the getter

Author: esamattis

test/components/connect.spec.js

@@ -1097,7 +1097,6 @@ describe('React', () => {
 
       expect(() => decorated.someInstanceMethod()).toThrow();
       expect(decorated.getWrappedInstance().someInstanceMethod()).toBe(someData);
-      expect(decorated.refs.wrappedInstance.someInstanceMethod()).toBe(someData);
     });
 
     it('should wrap impure components without supressing updates', () => {