chore(trace-viewer): only offer "Display Aria" when the trace has both snapshot kinds

[Pavel Feldman (pavelfeldman)]

Summary

• Disable the "Display Aria" setting when the trace has only DOM snapshots or only aria snapshots — there is nothing to switch between.
• In that case the snapshot tab ignores the stored setting and displays whatever the trace has.

[github-actions]

Test results for "tests 1"

2 flaky

⚠️ [chromium-library] › library/video.spec.ts:736 › screencast › should work with video+trace `@chromium-ubuntu-22.04-arm-node20`
⚠️ [firefox-page] › page/page-goto.spec.ts:90 › should work with Cross-Origin-Opener-Policy `@firefox-ubuntu-22.04-node20`

51314 passed, 1239 skipped

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Merge workflow run.

[github-actions]

Test results for "MCP"

1 failed
❌ [chromium] › mcp/http.spec.ts:105 › http transport browser lifecycle (isolated) @mcp-ubuntu-latest-chromium

8258 passed, 1361 skipped

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Merge workflow run.

[github-actions]

🟢 CI is clear — the one failure is a pre-existing flake

Hi, I'm the Playwright bot and I took a look at the failing CI. The single real failure is mcp/http.spec.ts:105 › http transport browser lifecycle (isolated) on chromium, and it's a known flake unrelated to this PR — which only touches trace-viewer UI.

Details

This PR (chore(trace-viewer): only offer "Display Aria" ...) changes trace-viewer React components and traceModel.ts. Nothing here touches the MCP HTTP transport or browser lifecycle.

Pre-existing flake / infra

• [chromium] › mcp/http.spec.ts:105 › http transport browser lifecycle (isolated) — pre-existing flake. Across the test-results DB it failed 6 of 740 runs (0.8%), passed the other 734, always with the same signature Test timeout of 30000ms exceeded. The other failures are on unrelated SHAs and PRs (e.g. test(components): restore web and html-reporter component tests #41889, feat(test runner): add fixture resources #41844, plus several push runs), none of which touch trace-viewer. This PR doesn't exercise the MCP HTTP transport at all, so it can't be the cause.

Not real failures

• [chromium-library] › library/video.spec.ts:736 › should work with video+trace and [firefox-page] › page/page-goto.spec.ts:90 › should work with Cross-Origin-Opener-Policy — reported flaky (passed on retry), nothing to triage.

Net: no failure is attributable to this PR.

_{Triaged by the Playwright bot - agent run}