Remove spy

Doesn't seem necessary and it breaks the other tests.

Author: sebmarkbage

Diff for: packages/react-dom/src/__tests__/ReactComponent-test.js

@@ -134,8 +134,6 @@ describe('ReactComponent', () => {
 
   // @gate !disableStringRefs
   it('string refs do not detach and reattach on every render', async () => {
-    spyOnDev(console, 'error').mockImplementation(() => {});
-
     let refVal;
     class Child extends React.Component {
       componentDidUpdate() {