keep-alive: 补充测试例，没有测出上个组件被成功移除的情况

pages/built-in-component/keep-alive/keep-alive.test.js

@@ -29,7 +29,9 @@ describe('keep-alive', () => {
 		const activatedNum = await page.$('#activated-num')
     expect(await activatedNum.text()).toBe('activated num: 1')
     const deactivatedNum = await page.$('#deactivated-num')
-    expect(await deactivatedNum.text()).toBe('deactivated num: 0')
+    expect(await deactivatedNum.text()).toBe('deactivated num: 0')
+    const shouldExcludeBtns2 = await page.$$('.should-exclude-btn')
+    expect(shouldExcludeBtns2.length).toBe(0)
 
     const counterBtns = await page.$$('.counter-btn')
     for (let i = 0; i < counterBtns.length; i++) {