[playwright] [Bug]: WebKit page.goto hangs when Playwright.provisionalLoadFailed arrives before the document requestWillBeSent

## Observed symptom [Bug]: WebKit page.goto hangs when Playwright.provisionalLoadFailed arrives before the document requestWillBeSent 1.62.1 (the same code is on `main` as of 2026-09-27) Against a real browser this is intermittent: one of about 340 navigations in a run, on Linux x64 WebKit r2361 (headless), where a fresh page navigates to a COOP+COEP document. It reproduces deterministically when a stub browser on the WebKit inspector pipe replays the protocol order we recorded: ## Environment GitHub microsoft/playwright #42957 ## Trigger / context Public GitHub report in microsoft/playwright (FRESH_7D). ## Source evidence - https://github.com/microsoft/playwright/issues/42957 (2026-09-30T11:30:30Z) — evidence_class: PRIMARY_ISSUE_REPORT — #42957 ## Freshness - classification: FRESH_7D - retrieved_at: 2026-10-02T09:52:00.922591Z - scout_id: C8e86b5f398 ## Scout notes This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome. Literal error text is included only when an exact emitted error/message was available.