Fixes WPT /html/dom/documents/resource-metadata-management/
document-lastModified.html (0/1 -> 1/1) and document-lastModified-01.html
(0/3 -> 3/3): document.lastModified was missing entirely.
The getter reports the navigation response's Last-Modified header
(already captured on the frame), parsed as an RFC 822 date and
formatted in the user's local time zone as "MM/DD/YYYY hh:mm:ss" via
libc localtime_r, matching what scripts derive from `new Date(...)`.
Documents without such a header - including script-created ones, which
don't inherit the frame's headers - report the current time, as the
spec requires.
Coverage: both files above fully green.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
7ef362316e