Covers _accept_language, _font_metrics_for_platform, Windows GPU/MSAA
clearing, Windows canvas noise mask (intel path), Windows WebGL extension
clearing, timezone handling, extra_prefs overlay (add/delete/override/no-op),
dark-theme system colors palette, locale normalization, Xvfb-key absence on
Windows, virtual_display sandbox workaround, and seed-derived LAN IP.
Linux-specific branches are intentionally not covered in this commit per
scoping instruction; they remain available in the plan for a follow-up
pass when running on Linux.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
chrissbaumann
54ae310bf2