According to YC News, the components in the entire repository are almost entirely unoriginal (and haven't even been implemented yet):
- Servo's HTML parser
- Servo's CSS parser
- QuickJS for JS
- Selectors for CSS selector matching
- resvg for SVG rendering
- egui, wgpu, and tiny-skia for rendering
- tungstenite for WebSocket support
And all of that has 3 million lines!