test(NavBar): update test cases

src/action-bar-button/test/__snapshots__/index.spec.js.snap

@@ -1,6 +1,6 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`should render default slot and match snapshot 1`] = `
+exports[`should render default slot correctly 1`] = `
 <button type="button" class="van-button van-button--default van-button--large van-action-bar-button">
   <div class="van-button__content">
     <!----><span class="van-button__text">Content</span>

src/action-bar-button/test/index.spec.js

@@ -1,7 +1,7 @@
 import { mount } from '@vue/test-utils';
 import ActionBarButton from '..';
 
-test('should render default slot and match snapshot', () => {
+test('should render default slot correctly', () => {
   const wrapper = mount(ActionBarButton, {
     slots: {
       default: 'Content',