fix: correct <summary> element behavior

[nn-morishita]

This PR addresses #2626.

The issue is that

element behavior is inconsistent with the real browser.

I verified this in a real browser, and the issue still occurs.

Reproduction:
https://stackblitz.com/edit/vitejs-vite-qxxwzrgz?file=src%2Fcomponents%2Ftests%2FDetailsComponent.test.ts

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[cexbrayat]

Thanks for the PR!

I don't think this is enough though. The PR makes <summary> skip ancestor visibility checks entirely in isElementVisible.
That means a <summary> can be reported visible even when one of its ancestors is hidden (for example display: none), which is a regression because hidden ancestors should make descendants not visible.

pseudo-test to reproduce (did not run it, so maybe it needs tweaking):

it('should consider a summary as hidden when an ancestor is hidden', () => {
  const HiddenAncestorSummary = defineComponent({
    template: `
      <div style="display: none;">
        <details>
          <summary>Summary</summary>
        </details>
      </div>
    `
  })

  const wrapper = mount(HiddenAncestorSummary)
  expect(wrapper.find('summary').isVisible()).toBe(false)
})

I also think the PR treats any <summary> inside a <details> as visible, regardless of structure.
That is too broad: only the primary summary should be visible in a closed <details>. A nested <summary> inside closed details content should remain hidden.

it('should consider a summary as hidden when nested inside closed details content', () => {
  const NestedSummaryInClosedDetails = defineComponent({
    template: `
      <details>
        <summary>Main summary</summary>
        <div>
          <summary>Nested summary</summary>
        </div>
      </details>
    `
  })

  const wrapper = mount(NestedSummaryInClosedDetails)
  const summaries = wrapper.findAll('summary')

  expect(summaries[0].isVisible()).toBe(true)
  expect(summaries[1].isVisible()).toBe(false)
});