test: todomvc case failed in windows and some linux os (#1899)

[Alanscut]

As clear-completed button is part of footer, although we expect await click('footer') will trigger the footer element, however it actually triggered the clear-completed button, so the next asserts will failed. 4.0 branch has the same problem.

vuex/test/e2e/todomvc.spec.js

Lines 123 to 125 in c9dbb13

	await click('footer') // blur
	expect(await count('.todo.editing')).toBe(0)
	expect(await text('.todo:nth-child(1) label')).toBe('edited!')

change click footer to .todo-count will make sure test cases pass, which could fix #1899.

[kiaking]

Ah thanks! Didn't see this PR. Yap, this is working and seems to be good fix. Thanks a lot 🙌