If you're okay with using Gecko instead of Webkit, the headless branch does compile into a standalone executable you can fork out to, it's what we do. The issu

If you're okay with using Gecko instead of Webkit, the headless branch does compile into a standalone executable you can fork out to, it's what we do. The issue with Gecko was less about rendering offscreen and more about rendering widgets (dropdowns, input boxes, etc.) which are normally handled by the windowing system.