export expect from jest-circus as well for easy import

- so all the test globals (except for 'jest') can be imported from
  jest-circus, no need to import from 'expect' as well
  - jest-circus sets the expect global, so would make sense that you
    could import from it as well

packages/jest-circus/src/index.ts

@@ -12,6 +12,8 @@ import {ErrorWithStack, isPromise} from 'jest-util';
 import {Circus, Global} from '@jest/types';
 import {dispatch} from './state';
 
+import expect = require('expect')
+
 type THook = (fn: Circus.HookFn, timeout?: number) => void;
 type DescribeFn = (
   blockName: Circus.BlockName,
@@ -221,6 +223,7 @@ export {
   xdescribe,
   fit,
   fdescribe,
+  expect,
 };
 export default {
   afterAll,
@@ -235,4 +238,5 @@ export default {
   xdescribe,
   fit,
   fdescribe,
+  expect,
 };