A display-p3 Canvas Names the CPU Chrome Runs On

Chrome rasterises an sRGB canvas to the same pixels on every machine we measured. Draw the same arc and line on a display-p3 canvas and Chrome on arm64 returns different pixels from Chrome on x86-64, because Skia’s raster pipeline rounds antialiased edges with an exact divide on ARM NEON and an approximate one on x86. Measured in Chrome 155 on macOS, Android, Windows and Linux, and confirmed with the operating system held fixed by running the same Chromium 155 package as amd64 and as arm64 on one Linux host.