fix(webkit): use native checkVisibility for element visibility

[Yury Semikhatsky (yury-s)]

Summary

• Use native Element.checkVisibility() in WebKit too; the WebKit bug that required the manual fallback is fixed for <details> and unslotted content.
• Fixes content of a <details> nested inside a closed <details> being reported as visible in WebKit.
• Drop the fallback for browsers without checkVisibility(); minimum supported versions are now Electron 21 and Chrome 105 on Android.

Supersedes #42951.

[github-actions]

Hi, I'm the Playwright bot and I took a first look at the CI failures.

🔴 One failure looks caused by this PR

mcp/core.spec.ts:170 › browser_select_option (multiple) fails on WebKit on all three OSes. The <option>s inside <select multiple> no longer get [ref=…], so WebKit's native checkVisibility() now reports them as hidden.

Details

Checked against head b281472. The "tests 1" run is green apart from flakes. The MCP run has 5 failures in 3 groups. One group is a clear regression from the checkVisibility switch. One is a known flake. One is probably unrelated but not proven.

Caused by this PR

• [webkit] › mcp/core.spec.ts:170 › browser_select_option (multiple): fails on ubuntu, macos and windows. The snapshot still lists the options, but they have lost their refs:

  -   - option "Foo" [ref=e3]
  +   - option "Foo"
  

  Refs only go to elements that pass isElementVisible. The PR removes the WebKit fallback in domUtils.ts::computeElementStyleVisibilityVisible and calls element.checkVisibility() unconditionally. WebKit returns false for <option> in a listbox, so those options are now treated as invisible. Before this PR the test had 0 failures in 738 WebKit runs. The fix probably belongs in computeElementStyleVisibilityVisible, for example by skipping checkVisibility() for OPTION/OPTGROUP, as the new roleUtils.ts comment already assumes. Also add a locator-is-visible test that covers options in <select multiple> on WebKit.

Pre-existing flake / infra

• [firefox] › mcp/cli-core.spec.ts:57 › click link (windows): the click times out after "performing click action". The test-results DB has this test on firefox failing in 5 of 725 runs, including push runs on main and fix(aria): annotate aria-hidden elements in AI snapshots #42268. It flips verdict and has nothing to do with the visibility change.

Uncertain

• [chrome] › mcp/annotate.spec.ts:137 › should abort MCP annotation when last screenshot is removed (windows): fails with Target page, context or browser has been closed / MCP error -32000: Connection closed, which looks like the MCP process died rather than a visibility problem. On chrome it has 0 failures in 737 runs. The same test does fail on unrelated PRs under other projects: msedge 4/716 (e.g. chore(coverage): istanbul instrumentation for the trace viewer and html reporter #42785, fix(chromium): stop disabling BoundaryEventDispatchTracksNodeRemoval #42294) and firefox 3/725 (e.g. fix(mcp): do not close browser while tool call is running #42696, fix(reporter): fail perfetto writes when the output stream errors #42715). That leans towards a flake, but it isn't proof for chrome. A green rerun would settle it.

_{Triaged by the Playwright bot - agent run}

[github-actions]

Test results for "tests 1"

5 flaky

⚠️ [chromium-library] › library/video.spec.ts:762 › screencast › should work with video+trace `@chromium-ubuntu-22.04-arm-node20`
⚠️ [chromium-library] › library/beforeunload.spec.ts:130 › should support dismissing the dialog multiple times `@chromium-ubuntu-22.04-node24`
⚠️ [chromium-library] › library/chromium/chromium.spec.ts:301 › should report intercepted service worker requests in HAR `@chromium-ubuntu-22.04-node20`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:257 › third party 'Partitioned;' cookies `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:470 › top level 'Partitioned;' cookie and same origin iframe `@firefox-ubuntu-22.04-node20`

52331 passed, 1243 skipped

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Merge workflow run.

[github-actions]

Test results for "MCP"

8790 passed, 1480 skipped

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Merge workflow run.