test(e2e): work around Playwright WebKit click and session bugs

[rgaignault]

Motivation

Running the e2e suite with --project=webkit currently fails on some click-action and session-dependent scenario. Two unrelated quirks in Playwright's WebKit fork combine to silently break the SDK:

1. Trusted PointerEvent.timeStamp returns a Cocoa-epoch-derived value (~8e11 ms) instead of a DOMHighResTimeStamp. The SDK feeds it into relativeToClocks(...) in trackClickActions, computes a click-start ~25 years in the future, and the "clock looks weird" guard discards every click.
2. window.cookieStore.set() resolves without error but does not persist. The next poll sees an empty cookie, handleStateChange treats it as an expired session within ~50ms, and every later event is dropped by the session/view assembly hook.

Changes

• Add a WEBKIT_PLAYWRIGHT_WORKAROUND init script in test/e2e/lib/framework/createTest.ts.
• Apply it via context.addInitScript(...) in declareTest when browserName === 'webkit'.

The workaround wraps Event.prototype.timeStamp to fall back to performance.now() when the raw value is implausibly large (>1 year), and removes window.cookieStore so the SDK takes its document.cookie fallback (which works correctly on Playwright WebKit). Scoped to test infrastructure — no SDK behaviour change.

Test instructions

yarn playwright test --config test/e2e/playwright.config.ts --project=webkit test/e2e/scenario/rum/actions.scenario.ts should pass all three variants. Without this change, all three fail.

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.
• Updated documentation and/or relevant AGENTS.md file

[cit-pr-commenter-54b7da]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	169.51 KiB	169.51 KiB	0 B	0.00%	✅
Rum Profiler	5.97 KiB	5.97 KiB	0 B	0.00%	✅
Rum Recorder	21.23 KiB	21.23 KiB	0 B	0.00%	✅
Logs	54.70 KiB	54.70 KiB	0 B	0.00%	✅
Rum Slim	127.85 KiB	127.85 KiB	0 B	0.00%	✅
Worker	22.99 KiB	22.99 KiB	0 B	0.00%	✅

🚀 CPU Performance

Action Name	Base CPU Time (ms)	Local CPU Time (ms)	𝚫%
RUM - add global context	0.0021	0.0027	+28.57%
RUM - add action	0.0105	0.0158	+50.48%
RUM - add error	0.0097	0.0143	+47.42%
RUM - add timing	0.0004	0.0005	+25.00%
RUM - start view	0.0092	0.0162	+76.09%
RUM - start/stop session replay recording	0.0007	0.001	+42.86%
Logs - log message	0.0139	0.0168	+20.86%

🧠 Memory Performance

Action Name	Base Memory Consumption	Local Memory Consumption	𝚫
RUM - add global context	38.24 KiB	37.52 KiB	-729 B
RUM - add action	64.64 KiB	63.02 KiB	-1.62 KiB
RUM - add timing	36.73 KiB	38.20 KiB	+1.46 KiB
RUM - add error	70.01 KiB	68.01 KiB	-2.00 KiB
RUM - start/stop session replay recording	45.58 KiB	41.24 KiB	-4.33 KiB
RUM - start view	483.88 KiB	487.51 KiB	+3.64 KiB
Logs - log message	55.00 KiB	54.34 KiB	-669 B

🔗 RealWorld

[datadog-datadog-prod-us1]

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 76.96% (+0.00%)

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