Remove unnecessary error overriding in (#19949)

packages/shared/__tests__/ReactErrorProd-test.internal.js

@@ -11,29 +11,11 @@
 let formatProdErrorMessage;
 
 describe('ReactErrorProd', () => {
-  let globalErrorMock;
-
   beforeEach(() => {
-    if (!__DEV__) {
-      // In production, our Jest environment overrides the global Error
-      // class in order to decode error messages automatically. However
-      // this is a single test where we actually *don't* want to decode
-      // them. So we assert that the OriginalError exists, and temporarily
-      // set the global Error object back to it.
-      globalErrorMock = global.Error;
-      global.Error = globalErrorMock.OriginalError;
-      expect(typeof global.Error).toBe('function');
-    }
     jest.resetModules();
     formatProdErrorMessage = require('shared/formatProdErrorMessage').default;
   });
 
-  afterEach(() => {
-    if (!__DEV__) {
-      global.Error = globalErrorMock;
-    }
-  });
-
   it('should throw with the correct number of `%s`s in the URL', () => {
     expect(formatProdErrorMessage(124, 'foo', 'bar')).toEqual(
       'Minified React error #124; visit ' +