Playwright Patches Critical Hang in Worker Response Headers

This patch addresses a critical failure in Playwright's public API: response.allHeaders() could hang indefinitely on worker scripts in iframes instead of returning headers or failing gracefully. The fix ensures API reliability by providing a bounded fallback to provisional headers, maintaining Playwright's contract with developers. For teams building complex web applications with worker architectures, this eliminates a source of unpredictable test timeouts and improves automation reliability.